22 files changed, 1571 insertions, 509 deletions

diff --git a/backend/Dockerfile b/backend/Dockerfile
index 1d1523d..acf7a68 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -1,6 +1,9 @@
 FROM golang:1.22.3 AS builder
 
 WORKDIR /build
+COPY go.mod go.sum ./
+RUN go mod download
+
 COPY . /build
 RUN go build -o /build/server .
 
diff --git a/backend/api/generated.go b/backend/api/generated.go
index 921f4b3..e39e3ba 100644
--- a/backend/api/generated.go
+++ b/backend/api/generated.go
@@ -32,6 +32,11 @@ const (
 	WaitingStart   GameState = "waiting_start"
 )
 
+// Defines values for GamePlayerMessageS2CExecResultPayloadStatus.
+const (
+	Success GamePlayerMessageS2CExecResultPayloadStatus = "success"
+)
+
 // Game defines model for Game.
 type Game struct {
 	DisplayName     string    `json:"display_name"`
@@ -45,6 +50,79 @@ type Game struct {
 // GameState defines model for Game.State.
 type GameState string
 
+// GamePlayerMessage defines model for GamePlayerMessage.
+type GamePlayerMessage struct {
+	union json.RawMessage
+}
+
+// GamePlayerMessageC2S defines model for GamePlayerMessageC2S.
+type GamePlayerMessageC2S struct {
+	union json.RawMessage
+}
+
+// GamePlayerMessageC2SCode defines model for GamePlayerMessageC2SCode.
+type GamePlayerMessageC2SCode struct {
+	Data GamePlayerMessageC2SCodePayload `json:"data"`
+	Type string                          `json:"type"`
+}
+
+// GamePlayerMessageC2SCodePayload defines model for GamePlayerMessageC2SCodePayload.
+type GamePlayerMessageC2SCodePayload struct {
+	Code string `json:"code"`
+}
+
+// GamePlayerMessageC2SEntry defines model for GamePlayerMessageC2SEntry.
+type GamePlayerMessageC2SEntry struct {
+	Type string `json:"type"`
+}
+
+// GamePlayerMessageC2SReady defines model for GamePlayerMessageC2SReady.
+type GamePlayerMessageC2SReady struct {
+	Type string `json:"type"`
+}
+
+// GamePlayerMessageS2C defines model for GamePlayerMessageS2C.
+type GamePlayerMessageS2C struct {
+	union json.RawMessage
+}
+
+// GamePlayerMessageS2CExecResult defines model for GamePlayerMessageS2CExecResult.
+type GamePlayerMessageS2CExecResult struct {
+	Data GamePlayerMessageS2CExecResultPayload `json:"data"`
+	Type string                                `json:"type"`
+}
+
+// GamePlayerMessageS2CExecResultPayload defines model for GamePlayerMessageS2CExecResultPayload.
+type GamePlayerMessageS2CExecResultPayload struct {
+	Score  *int                                        `json:"score"`
+	Status GamePlayerMessageS2CExecResultPayloadStatus `json:"status"`
+}
+
+// GamePlayerMessageS2CExecResultPayloadStatus defines model for GamePlayerMessageS2CExecResultPayload.Status.
+type GamePlayerMessageS2CExecResultPayloadStatus string
+
+// GamePlayerMessageS2CPrepare defines model for GamePlayerMessageS2CPrepare.
+type GamePlayerMessageS2CPrepare struct {
+	Data GamePlayerMessageS2CPreparePayload `json:"data"`
+	Type string                             `json:"type"`
+}
+
+// GamePlayerMessageS2CPreparePayload defines model for GamePlayerMessageS2CPreparePayload.
+type GamePlayerMessageS2CPreparePayload struct {
+	Problem Problem `json:"problem"`
+}
+
+// GamePlayerMessageS2CStart defines model for GamePlayerMessageS2CStart.
+type GamePlayerMessageS2CStart struct {
+	Data GamePlayerMessageS2CStartPayload `json:"data"`
+	Type string                           `json:"type"`
+}
+
+// GamePlayerMessageS2CStartPayload defines model for GamePlayerMessageS2CStartPayload.
+type GamePlayerMessageS2CStartPayload struct {
+	StartAt int `json:"start_at"`
+}
+
 // JwtPayload defines model for JwtPayload.
 type JwtPayload struct {
 	DisplayName string  `json:"display_name"`
@@ -67,6 +145,11 @@ type GetGamesParams struct {
 	Authorization string `json:"Authorization"`
 }
 
+// GetGamesGameIdParams defines parameters for GetGamesGameId.
+type GetGamesGameIdParams struct {
+	Authorization string `json:"Authorization"`
+}
+
 // PostLoginJSONBody defines parameters for PostLogin.
 type PostLoginJSONBody struct {
 	Password string `json:"password"`
@@ -76,11 +159,252 @@ type PostLoginJSONBody struct {
 // PostLoginJSONRequestBody defines body for PostLogin for application/json ContentType.
 type PostLoginJSONRequestBody PostLoginJSONBody
 
+// AsGamePlayerMessageS2C returns the union data inside the GamePlayerMessage as a GamePlayerMessageS2C
+func (t GamePlayerMessage) AsGamePlayerMessageS2C() (GamePlayerMessageS2C, error) {
+	var body GamePlayerMessageS2C
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageS2C overwrites any union data inside the GamePlayerMessage as the provided GamePlayerMessageS2C
+func (t *GamePlayerMessage) FromGamePlayerMessageS2C(v GamePlayerMessageS2C) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageS2C performs a merge with any union data inside the GamePlayerMessage, using the provided GamePlayerMessageS2C
+func (t *GamePlayerMessage) MergeGamePlayerMessageS2C(v GamePlayerMessageS2C) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+// AsGamePlayerMessageC2S returns the union data inside the GamePlayerMessage as a GamePlayerMessageC2S
+func (t GamePlayerMessage) AsGamePlayerMessageC2S() (GamePlayerMessageC2S, error) {
+	var body GamePlayerMessageC2S
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageC2S overwrites any union data inside the GamePlayerMessage as the provided GamePlayerMessageC2S
+func (t *GamePlayerMessage) FromGamePlayerMessageC2S(v GamePlayerMessageC2S) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageC2S performs a merge with any union data inside the GamePlayerMessage, using the provided GamePlayerMessageC2S
+func (t *GamePlayerMessage) MergeGamePlayerMessageC2S(v GamePlayerMessageC2S) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+func (t GamePlayerMessage) MarshalJSON() ([]byte, error) {
+	b, err := t.union.MarshalJSON()
+	return b, err
+}
+
+func (t *GamePlayerMessage) UnmarshalJSON(b []byte) error {
+	err := t.union.UnmarshalJSON(b)
+	return err
+}
+
+// AsGamePlayerMessageC2SEntry returns the union data inside the GamePlayerMessageC2S as a GamePlayerMessageC2SEntry
+func (t GamePlayerMessageC2S) AsGamePlayerMessageC2SEntry() (GamePlayerMessageC2SEntry, error) {
+	var body GamePlayerMessageC2SEntry
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageC2SEntry overwrites any union data inside the GamePlayerMessageC2S as the provided GamePlayerMessageC2SEntry
+func (t *GamePlayerMessageC2S) FromGamePlayerMessageC2SEntry(v GamePlayerMessageC2SEntry) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageC2SEntry performs a merge with any union data inside the GamePlayerMessageC2S, using the provided GamePlayerMessageC2SEntry
+func (t *GamePlayerMessageC2S) MergeGamePlayerMessageC2SEntry(v GamePlayerMessageC2SEntry) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+// AsGamePlayerMessageC2SReady returns the union data inside the GamePlayerMessageC2S as a GamePlayerMessageC2SReady
+func (t GamePlayerMessageC2S) AsGamePlayerMessageC2SReady() (GamePlayerMessageC2SReady, error) {
+	var body GamePlayerMessageC2SReady
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageC2SReady overwrites any union data inside the GamePlayerMessageC2S as the provided GamePlayerMessageC2SReady
+func (t *GamePlayerMessageC2S) FromGamePlayerMessageC2SReady(v GamePlayerMessageC2SReady) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageC2SReady performs a merge with any union data inside the GamePlayerMessageC2S, using the provided GamePlayerMessageC2SReady
+func (t *GamePlayerMessageC2S) MergeGamePlayerMessageC2SReady(v GamePlayerMessageC2SReady) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+// AsGamePlayerMessageC2SCode returns the union data inside the GamePlayerMessageC2S as a GamePlayerMessageC2SCode
+func (t GamePlayerMessageC2S) AsGamePlayerMessageC2SCode() (GamePlayerMessageC2SCode, error) {
+	var body GamePlayerMessageC2SCode
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageC2SCode overwrites any union data inside the GamePlayerMessageC2S as the provided GamePlayerMessageC2SCode
+func (t *GamePlayerMessageC2S) FromGamePlayerMessageC2SCode(v GamePlayerMessageC2SCode) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageC2SCode performs a merge with any union data inside the GamePlayerMessageC2S, using the provided GamePlayerMessageC2SCode
+func (t *GamePlayerMessageC2S) MergeGamePlayerMessageC2SCode(v GamePlayerMessageC2SCode) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+func (t GamePlayerMessageC2S) MarshalJSON() ([]byte, error) {
+	b, err := t.union.MarshalJSON()
+	return b, err
+}
+
+func (t *GamePlayerMessageC2S) UnmarshalJSON(b []byte) error {
+	err := t.union.UnmarshalJSON(b)
+	return err
+}
+
+// AsGamePlayerMessageS2CPrepare returns the union data inside the GamePlayerMessageS2C as a GamePlayerMessageS2CPrepare
+func (t GamePlayerMessageS2C) AsGamePlayerMessageS2CPrepare() (GamePlayerMessageS2CPrepare, error) {
+	var body GamePlayerMessageS2CPrepare
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageS2CPrepare overwrites any union data inside the GamePlayerMessageS2C as the provided GamePlayerMessageS2CPrepare
+func (t *GamePlayerMessageS2C) FromGamePlayerMessageS2CPrepare(v GamePlayerMessageS2CPrepare) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageS2CPrepare performs a merge with any union data inside the GamePlayerMessageS2C, using the provided GamePlayerMessageS2CPrepare
+func (t *GamePlayerMessageS2C) MergeGamePlayerMessageS2CPrepare(v GamePlayerMessageS2CPrepare) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+// AsGamePlayerMessageS2CStart returns the union data inside the GamePlayerMessageS2C as a GamePlayerMessageS2CStart
+func (t GamePlayerMessageS2C) AsGamePlayerMessageS2CStart() (GamePlayerMessageS2CStart, error) {
+	var body GamePlayerMessageS2CStart
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageS2CStart overwrites any union data inside the GamePlayerMessageS2C as the provided GamePlayerMessageS2CStart
+func (t *GamePlayerMessageS2C) FromGamePlayerMessageS2CStart(v GamePlayerMessageS2CStart) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageS2CStart performs a merge with any union data inside the GamePlayerMessageS2C, using the provided GamePlayerMessageS2CStart
+func (t *GamePlayerMessageS2C) MergeGamePlayerMessageS2CStart(v GamePlayerMessageS2CStart) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+// AsGamePlayerMessageS2CExecResult returns the union data inside the GamePlayerMessageS2C as a GamePlayerMessageS2CExecResult
+func (t GamePlayerMessageS2C) AsGamePlayerMessageS2CExecResult() (GamePlayerMessageS2CExecResult, error) {
+	var body GamePlayerMessageS2CExecResult
+	err := json.Unmarshal(t.union, &body)
+	return body, err
+}
+
+// FromGamePlayerMessageS2CExecResult overwrites any union data inside the GamePlayerMessageS2C as the provided GamePlayerMessageS2CExecResult
+func (t *GamePlayerMessageS2C) FromGamePlayerMessageS2CExecResult(v GamePlayerMessageS2CExecResult) error {
+	b, err := json.Marshal(v)
+	t.union = b
+	return err
+}
+
+// MergeGamePlayerMessageS2CExecResult performs a merge with any union data inside the GamePlayerMessageS2C, using the provided GamePlayerMessageS2CExecResult
+func (t *GamePlayerMessageS2C) MergeGamePlayerMessageS2CExecResult(v GamePlayerMessageS2CExecResult) error {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return err
+	}
+
+	merged, err := runtime.JSONMerge(t.union, b)
+	t.union = merged
+	return err
+}
+
+func (t GamePlayerMessageS2C) MarshalJSON() ([]byte, error) {
+	b, err := t.union.MarshalJSON()
+	return b, err
+}
+
+func (t *GamePlayerMessageS2C) UnmarshalJSON(b []byte) error {
+	err := t.union.UnmarshalJSON(b)
+	return err
+}
+
 // ServerInterface represents all server handlers.
 type ServerInterface interface {
 	// List games
 	// (GET /games)
 	GetGames(ctx echo.Context, params GetGamesParams) error
+	// Get a game
+	// (GET /games/{game_id})
+	GetGamesGameId(ctx echo.Context, gameId int, params GetGamesGameIdParams) error
 	// User login
 	// (POST /login)
 	PostLogin(ctx echo.Context) error
@@ -128,6 +452,44 @@ func (w *ServerInterfaceWrapper) GetGames(ctx echo.Context) error {
 	return err
 }
 
+// GetGamesGameId converts echo context to params.
+func (w *ServerInterfaceWrapper) GetGamesGameId(ctx echo.Context) error {
+	var err error
+	// ------------- Path parameter "game_id" -------------
+	var gameId int
+
+	err = runtime.BindStyledParameterWithOptions("simple", "game_id", ctx.Param("game_id"), &gameId, runtime.BindStyledParameterOptions{ParamLocation: runtime.ParamLocationPath, Explode: false, Required: true})
+	if err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Invalid format for parameter game_id: %s", err))
+	}
+
+	// Parameter object where we will unmarshal all parameters from the context
+	var params GetGamesGameIdParams
+
+	headers := ctx.Request().Header
+	// ------------- Required header parameter "Authorization" -------------
+	if valueList, found := headers[http.CanonicalHeaderKey("Authorization")]; found {
+		var Authorization string
+		n := len(valueList)
+		if n != 1 {
+			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Expected one value for Authorization, got %d", n))
+		}
+
+		err = runtime.BindStyledParameterWithOptions("simple", "Authorization", valueList[0], &Authorization, runtime.BindStyledParameterOptions{ParamLocation: runtime.ParamLocationHeader, Explode: false, Required: true})
+		if err != nil {
+			return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Invalid format for parameter Authorization: %s", err))
+		}
+
+		params.Authorization = Authorization
+	} else {
+		return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Header parameter Authorization is required, but not found"))
+	}
+
+	// Invoke the callback with all the unmarshaled arguments
+	err = w.Handler.GetGamesGameId(ctx, gameId, params)
+	return err
+}
+
 // PostLogin converts echo context to params.
 func (w *ServerInterfaceWrapper) PostLogin(ctx echo.Context) error {
 	var err error
@@ -166,6 +528,7 @@ func RegisterHandlersWithBaseURL(router EchoRouter, si ServerInterface, baseURL
 	}
 
 	router.GET(baseURL+"/games", wrapper.GetGames)
+	router.GET(baseURL+"/games/:game_id", wrapper.GetGamesGameId)
 	router.POST(baseURL+"/login", wrapper.PostLogin)
 
 }
@@ -200,6 +563,35 @@ func (response GetGames403JSONResponse) VisitGetGamesResponse(w http.ResponseWri
 	return json.NewEncoder(w).Encode(response)
 }
 
+type GetGamesGameIdRequestObject struct {
+	GameId int `json:"game_id"`
+	Params GetGamesGameIdParams
+}
+
+type GetGamesGameIdResponseObject interface {
+	VisitGetGamesGameIdResponse(w http.ResponseWriter) error
+}
+
+type GetGamesGameId200JSONResponse Game
+
+func (response GetGamesGameId200JSONResponse) VisitGetGamesGameIdResponse(w http.ResponseWriter) error {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(200)
+
+	return json.NewEncoder(w).Encode(response)
+}
+
+type GetGamesGameId403JSONResponse struct {
+	Message string `json:"message"`
+}
+
+func (response GetGamesGameId403JSONResponse) VisitGetGamesGameIdResponse(w http.ResponseWriter) error {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(403)
+
+	return json.NewEncoder(w).Encode(response)
+}
+
 type PostLoginRequestObject struct {
 	Body *PostLoginJSONRequestBody
 }
@@ -235,6 +627,9 @@ type StrictServerInterface interface {
 	// List games
 	// (GET /games)
 	GetGames(ctx context.Context, request GetGamesRequestObject) (GetGamesResponseObject, error)
+	// Get a game
+	// (GET /games/{game_id})
+	GetGamesGameId(ctx context.Context, request GetGamesGameIdRequestObject) (GetGamesGameIdResponseObject, error)
 	// User login
 	// (POST /login)
 	PostLogin(ctx context.Context, request PostLoginRequestObject) (PostLoginResponseObject, error)
@@ -277,6 +672,32 @@ func (sh *strictHandler) GetGames(ctx echo.Context, params GetGamesParams) error
 	return nil
 }
 
+// GetGamesGameId operation middleware
+func (sh *strictHandler) GetGamesGameId(ctx echo.Context, gameId int, params GetGamesGameIdParams) error {
+	var request GetGamesGameIdRequestObject
+
+	request.GameId = gameId
+	request.Params = params
+
+	handler := func(ctx echo.Context, request interface{}) (interface{}, error) {
+		return sh.ssi.GetGamesGameId(ctx.Request().Context(), request.(GetGamesGameIdRequestObject))
+	}
+	for _, middleware := range sh.middlewares {
+		handler = middleware(handler, "GetGamesGameId")
+	}
+
+	response, err := handler(ctx, request)
+
+	if err != nil {
+		return err
+	} else if validResponse, ok := response.(GetGamesGameIdResponseObject); ok {
+		return validResponse.VisitGetGamesGameIdResponse(ctx.Response())
+	} else if response != nil {
+		return fmt.Errorf("unexpected response type: %T", response)
+	}
+	return nil
+}
+
 // PostLogin operation middleware
 func (sh *strictHandler) PostLogin(ctx echo.Context) error {
 	var request PostLoginRequestObject
@@ -309,20 +730,26 @@ func (sh *strictHandler) PostLogin(ctx echo.Context) error {
 // Base64 encoded, gzipped, json marshaled Swagger object
 var swaggerSpec = []string{
 
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-	"/yqVrshbpv9Hk+fEvG+q6pBgIyUZCVBJdXa++mg735snrLRKck8q9MKKP9TOQ/1hmon1yTjOqcP/YvJJ",
-	"Z+u2bdt/AwAA//+RpToKFwoAAA==",
+	"H4sIAAAAAAAC/9xX3W7jNhN9FX38CmwLCP7LItj6Lk23aRZb1Fi3V4vAoMWxzZQitRxqEzfQuxf8kWRZ",
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+	"o8VrC9qbd6H58HB639P98Qe1k9HPCro6ZJ4oucqo2TVNxjylW8DxvdrJ0X227TTFFWUplw3LDRVY1/1a",
+	"KQFU2tU5gm611bOLriPCLm1HYaH0prPc5cBJqzOtcHcxvKjL44hewETzzLa0TVx/7DhGHCMalbXRwVV4",
+	"NWiuMNyIo9gDqq4hp7s+PQfeU9zA3g7auuByo1yL4PcmV2JNjVaIkQWmJRXRA6yjq8UticlX0OhoIJPR",
+	"dDSxmFUGkmaczMnFaDKa2NmDmp0jbmxHBfdtC64oLKtuNLhldngDc+MWWBNNUzCg0bUMVlnkSw6uO/J6",
+	"CPUdBg93TtSNzWFJBesdUAa6Nr/KzU5p/rfbnhwy56+rlsuK5Tu7GDMl0ccym0zCuWNAurBolgmeOM/j",
+	"e/Qqqf01xVRRwg2kOOQgrA87QrWm+86BDE9kt6Fd8pGjidQm8hZFTN5OLl4RS1pPbrVgf1F6zRkDGVXZ",
+	"7pVu6WhIDJV/5wXzNKW27faxhcCKOGhv/BSm1aJXhfbjlp3QojsmKy3VE3Cviv7NwuwXXpv9K0fxf0w6",
+	"N2AiGgKz0hFq6++2TGGHYhYKzUe3xEMBND8pP3W9kI2MIj4ozY6G1vB0OrvoulheeVeGK7HaupvAphqL",
+	"sx6FRv0FRzfqo/0bHXz2d3HOyZDsL/1cscmF2Ec0NzuQxkIF5uU8Pbecb+VXKjiLEg3M7kUFnlXOpf8y",
+	"m5HSUZXOpsL/RNCRl3VRFMU/AQAA///TQodrghUAAA==",
 }
 
 // GetSwagger returns the content of the embedded swagger specification file
diff --git a/backend/api/handlers.go b/backend/api/handlers.go
index 54a3fc4..91cdbc8 100644
--- a/backend/api/handlers.go
+++ b/backend/api/handlers.go
@@ -133,6 +133,41 @@ func (h *ApiHandler) GetGames(ctx context.Context, request GetGamesRequestObject
 	}
 }
 
+func (h *ApiHandler) GetGamesGameId(ctx context.Context, request GetGamesGameIdRequestObject) (GetGamesGameIdResponseObject, error) {
+	// TODO: user permission
+	// user := ctx.Value("user").(*auth.JWTClaims)
+	gameId := request.GameId
+	row, err := h.q.GetGameById(ctx, int32(gameId))
+	if err != nil {
+		return nil, echo.NewHTTPError(http.StatusInternalServerError, err.Error())
+	}
+	var startedAt *int
+	if row.StartedAt.Valid {
+		startedAtTimestamp := int(row.StartedAt.Time.Unix())
+		startedAt = &startedAtTimestamp
+	}
+	var problem *Problem
+	if row.ProblemID.Valid && GameState(row.State) != Closed && GameState(row.State) != WaitingEntries {
+		if !row.Title.Valid || !row.Description.Valid {
+			panic("inconsistent data")
+		}
+		problem = &Problem{
+			ProblemId:   int(row.ProblemID.Int32),
+			Title:       row.Title.String,
+			Description: row.Description.String,
+		}
+	}
+	game := Game{
+		GameId:          int(row.GameID),
+		State:           GameState(row.State),
+		DisplayName:     row.DisplayName,
+		DurationSeconds: int(row.DurationSeconds),
+		StartedAt:       startedAt,
+		Problem:         problem,
+	}
+	return GetGamesGameId200JSONResponse(game), nil
+}
+
 func _assertJwtPayloadIsCompatibleWithJWTClaims() {
 	var c auth.JWTClaims
 	var p JwtPayload
diff --git a/backend/db/query.sql.go b/backend/db/query.sql.go
index 20a7dc1..1b9f392 100644
--- a/backend/db/query.sql.go
+++ b/backend/db/query.sql.go
@@ -11,6 +11,44 @@ import (
 	"github.com/jackc/pgx/v5/pgtype"
 )
 
+const getGameById = `-- name: GetGameById :one
+SELECT game_id, state, display_name, duration_seconds, created_at, started_at, games.problem_id, problems.problem_id, title, description FROM games
+LEFT JOIN problems ON games.problem_id = problems.problem_id
+WHERE games.game_id = $1
+LIMIT 1
+`
+
+type GetGameByIdRow struct {
+	GameID          int32
+	State           string
+	DisplayName     string
+	DurationSeconds int32
+	CreatedAt       pgtype.Timestamp
+	StartedAt       pgtype.Timestamp
+	ProblemID       pgtype.Int4
+	ProblemID_2     pgtype.Int4
+	Title           pgtype.Text
+	Description     pgtype.Text
+}
+
+func (q *Queries) GetGameById(ctx context.Context, gameID int32) (GetGameByIdRow, error) {
+	row := q.db.QueryRow(ctx, getGameById, gameID)
+	var i GetGameByIdRow
+	err := row.Scan(
+		&i.GameID,
+		&i.State,
+		&i.DisplayName,
+		&i.DurationSeconds,
+		&i.CreatedAt,
+		&i.StartedAt,
+		&i.ProblemID,
+		&i.ProblemID_2,
+		&i.Title,
+		&i.Description,
+	)
+	return i, err
+}
+
 const getUserAuthByUsername = `-- name: GetUserAuthByUsername :one
 SELECT users.user_id, username, display_name, icon_path, is_admin, created_at, user_auth_id, user_auths.user_id, auth_type, password_hash FROM users
 JOIN user_auths ON users.user_id = user_auths.user_id
@@ -172,3 +210,35 @@ func (q *Queries) ListGamesForPlayer(ctx context.Context, userID int32) ([]ListG
 	}
 	return items, nil
 }
+
+const updateGameStartedAt = `-- name: UpdateGameStartedAt :exec
+UPDATE games
+SET started_at = $2
+WHERE game_id = $1
+`
+
+type UpdateGameStartedAtParams struct {
+	GameID    int32
+	StartedAt pgtype.Timestamp
+}
+
+func (q *Queries) UpdateGameStartedAt(ctx context.Context, arg UpdateGameStartedAtParams) error {
+	_, err := q.db.Exec(ctx, updateGameStartedAt, arg.GameID, arg.StartedAt)
+	return err
+}
+
+const updateGameState = `-- name: UpdateGameState :exec
+UPDATE games
+SET state = $2
+WHERE game_id = $1
+`
+
+type UpdateGameStateParams struct {
+	GameID int32
+	State  string
+}
+
+func (q *Queries) UpdateGameState(ctx context.Context, arg UpdateGameStateParams) error {
+	_, err := q.db.Exec(ctx, updateGameState, arg.GameID, arg.State)
+	return err
+}
diff --git a/backend/game/client.go b/backend/game/client.go
new file mode 100644
index 0000000..7cd66a4
--- /dev/null
+++ b/backend/game/client.go
@@ -0,0 +1,113 @@
+package game
+
+import (
+	"encoding/json"
+	"log"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+type playerClient struct {
+	hub         *gameHub
+	conn        *websocket.Conn
+	s2cMessages chan playerMessageS2C
+}
+
+// Receives messages from the client and sends them to the hub.
+func (c *playerClient) readPump() {
+	defer func() {
+		log.Printf("closing client")
+		c.hub.unregisterPlayer <- c
+		c.conn.Close()
+	}()
+	c.conn.SetReadLimit(maxMessageSize)
+	c.conn.SetReadDeadline(time.Now().Add(pongWait))
+	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	for {
+		var rawMessage map[string]json.RawMessage
+		if err := c.conn.ReadJSON(&rawMessage); err != nil {
+			log.Printf("error: %v", err)
+			return
+		}
+		message, err := asPlayerMessageC2S(rawMessage)
+		if err != nil {
+			log.Printf("error: %v", err)
+			return
+		}
+		c.hub.playerC2SMessages <- &playerMessageC2SWithClient{c, message}
+	}
+}
+
+// Receives messages from the hub and sends them to the client.
+func (c *playerClient) writePump() {
+	ticker := time.NewTicker(pingPeriod)
+	defer func() {
+		ticker.Stop()
+		c.conn.Close()
+	}()
+	for {
+		select {
+		case message, ok := <-c.s2cMessages:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if !ok {
+				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
+				return
+			}
+
+			err := c.conn.WriteJSON(message)
+			if err != nil {
+				return
+			}
+		case <-ticker.C:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
+				return
+			}
+		}
+	}
+}
+
+type watcherClient struct {
+	hub         *gameHub
+	conn        *websocket.Conn
+	s2cMessages chan watcherMessageS2C
+}
+
+// Receives messages from the client and sends them to the hub.
+func (c *watcherClient) readPump() {
+	c.conn.SetReadLimit(maxMessageSize)
+	c.conn.SetReadDeadline(time.Now().Add(pongWait))
+	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+}
+
+// Receives messages from the hub and sends them to the client.
+func (c *watcherClient) writePump() {
+	ticker := time.NewTicker(pingPeriod)
+	defer func() {
+		ticker.Stop()
+		c.conn.Close()
+		log.Printf("closing watcher")
+		c.hub.unregisterWatcher <- c
+	}()
+	for {
+		select {
+		case message, ok := <-c.s2cMessages:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if !ok {
+				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
+				return
+			}
+
+			err := c.conn.WriteJSON(message)
+			if err != nil {
+				return
+			}
+		case <-ticker.C:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
+				return
+			}
+		}
+	}
+}
diff --git a/backend/game/game.go b/backend/game/game.go
deleted file mode 100644
index 9e63a1e..0000000
--- a/backend/game/game.go
+++ /dev/null
@@ -1,385 +0,0 @@
-package game
-
-import (
-	"context"
-	"log"
-	"time"
-
-	"github.com/gorilla/websocket"
-
-	"github.com/nsfisis/iosdc-2024-albatross/backend/api"
-	"github.com/nsfisis/iosdc-2024-albatross/backend/db"
-)
-
-type gameState = api.GameState
-
-const (
-	gameStateClosed         gameState = api.Closed
-	gameStateWaitingEntries gameState = api.WaitingEntries
-	gameStateWaitingStart   gameState = api.WaitingStart
-	gameStatePrepare        gameState = api.Prepare
-	gameStateStarting       gameState = api.Starting
-	gameStateGaming         gameState = api.Gaming
-	gameStateFinished       gameState = api.Finished
-)
-
-type game struct {
-	gameID          int
-	state           string
-	displayName     string
-	durationSeconds int
-	startedAt       *time.Time
-	problem         *problem
-}
-
-type problem struct {
-	problemID   int
-	title       string
-	description string
-}
-
-// func startGame(game *Game) {
-// 	if gameHubs[game.GameID] != nil {
-// 		return
-// 	}
-// 	gameHubs[game.GameID] = NewGameHub(game)
-// 	go gameHubs[game.GameID].Run()
-// }
-
-/*
-func handleGolfPost(w http.ResponseWriter, r *http.Request) {
-	var yourTeam string
-	waitingGolfGames := []Game{}
-	err := db.Select(&waitingGolfGames, "SELECT * FROM games WHERE type = $1 AND state = $2 ORDER BY created_at", gameTypeGolf, gameStateWaiting)
-	if err != nil {
-		http.Error(w, "Error getting games", http.StatusInternalServerError)
-		return
-	}
-	if len(waitingGolfGames) == 0 {
-		_, err = db.Exec("INSERT INTO games (type, state) VALUES ($1, $2)", gameTypeGolf, gameStateWaiting)
-		if err != nil {
-			http.Error(w, "Error creating game", http.StatusInternalServerError)
-			return
-		}
-		waitingGolfGames = []Game{}
-		err = db.Select(&waitingGolfGames, "SELECT * FROM games WHERE type = $1 AND state = $2 ORDER BY created_at", gameTypeGolf, gameStateWaiting)
-		if err != nil {
-			http.Error(w, "Error getting games", http.StatusInternalServerError)
-			return
-		}
-		yourTeam = "a"
-		startGame(&waitingGolfGames[0])
-	} else {
-		yourTeam = "b"
-		db.Exec("UPDATE games SET state = $1 WHERE game_id = $2", gameStateReady, waitingGolfGames[0].GameID)
-	}
-	waitingGame := waitingGolfGames[0]
-
-	http.Redirect(w, r, fmt.Sprintf("/golf/%d/%s/", waitingGame.GameID, yourTeam), http.StatusSeeOther)
-}
-*/
-
-type GameHub struct {
-	game              *game
-	clients           map[*GameClient]bool
-	receive           chan *MessageWithClient
-	register          chan *GameClient
-	unregister        chan *GameClient
-	watchers          map[*GameWatcher]bool
-	registerWatcher   chan *GameWatcher
-	unregisterWatcher chan *GameWatcher
-	state             int
-	finishTime        time.Time
-}
-
-func NewGameHub(game *game) *GameHub {
-	return &GameHub{
-		game:              game,
-		clients:           make(map[*GameClient]bool),
-		receive:           make(chan *MessageWithClient),
-		register:          make(chan *GameClient),
-		unregister:        make(chan *GameClient),
-		watchers:          make(map[*GameWatcher]bool),
-		registerWatcher:   make(chan *GameWatcher),
-		unregisterWatcher: make(chan *GameWatcher),
-		state:             0,
-	}
-}
-
-func (h *GameHub) Run() {
-	ticker := time.NewTicker(10 * time.Second)
-	defer func() {
-		ticker.Stop()
-	}()
-
-	for {
-		select {
-		case client := <-h.register:
-			h.clients[client] = true
-			log.Printf("client registered: %d", len(h.clients))
-		case client := <-h.unregister:
-			if _, ok := h.clients[client]; ok {
-				h.closeClient(client)
-			}
-			log.Printf("client unregistered: %d", len(h.clients))
-			if len(h.clients) == 0 {
-				h.Close()
-				return
-			}
-		case watcher := <-h.registerWatcher:
-			h.watchers[watcher] = true
-			log.Printf("watcher registered: %d", len(h.watchers))
-		case watcher := <-h.unregisterWatcher:
-			if _, ok := h.watchers[watcher]; ok {
-				h.closeWatcher(watcher)
-			}
-			log.Printf("watcher unregistered: %d", len(h.watchers))
-		case message := <-h.receive:
-			log.Printf("received message: %s", message.Message.Type)
-			switch message.Message.Type {
-			case "connect":
-				if h.state == 0 {
-					h.state = 1
-				} else if h.state == 1 {
-					h.state = 2
-					for client := range h.clients {
-						client.send <- &Message{Type: "prepare", Data: MessageDataPrepare{Problem: "1 から 100 までの FizzBuzz を実装せよ (終端を含む)。"}}
-					}
-				} else {
-					log.Printf("invalid state: %d", h.state)
-					h.closeClient(message.Client)
-				}
-			case "ready":
-				if h.state == 2 {
-					h.state = 3
-				} else if h.state == 3 {
-					h.state = 4
-					for client := range h.clients {
-						client.send <- &Message{Type: "start", Data: MessageDataStart{StartTime: time.Now().Add(10 * time.Second).UTC().Format(time.RFC3339)}}
-					}
-					h.finishTime = time.Now().Add(3 * time.Minute)
-				} else {
-					log.Printf("invalid state: %d", h.state)
-					h.closeClient(message.Client)
-				}
-			case "code":
-				if h.state == 4 {
-					code := message.Message.Data.(MessageDataCode).Code
-					message.Client.code = code
-					message.Client.send <- &Message{Type: "score", Data: MessageDataScore{Score: 100}}
-					if message.Client.score == nil {
-						message.Client.score = new(int)
-					}
-					*message.Client.score = 100
-
-					var scoreA, scoreB *int
-					var codeA, codeB string
-					for client := range h.clients {
-						if client.team == "a" {
-							scoreA = client.score
-							codeA = client.code
-						} else {
-							scoreB = client.score
-							codeB = client.code
-						}
-					}
-					for watcher := range h.watchers {
-						watcher.send <- &Message{
-							Type: "watch",
-							Data: MessageDataWatch{
-								Problem: "1 から 100 までの FizzBuzz を実装せよ (終端を含む)。",
-								ScoreA:  scoreA,
-								CodeA:   codeA,
-								ScoreB:  scoreB,
-								CodeB:   codeB,
-							},
-						}
-					}
-				} else {
-					log.Printf("invalid state: %d", h.state)
-					h.closeClient(message.Client)
-				}
-			default:
-				log.Printf("unknown message type: %s", message.Message.Type)
-				h.closeClient(message.Client)
-			}
-		case <-ticker.C:
-			log.Printf("state: %d", h.state)
-			if h.state == 4 {
-				if time.Now().After(h.finishTime) {
-					h.state = 5
-					clientAndScores := make(map[*GameClient]*int)
-					for client := range h.clients {
-						clientAndScores[client] = client.score
-					}
-					for client, score := range clientAndScores {
-						var opponentScore *int
-						for c2, s2 := range clientAndScores {
-							if c2 != client {
-								opponentScore = s2
-								break
-							}
-						}
-						client.send <- &Message{Type: "finish", Data: MessageDataFinish{YourScore: score, OpponentScore: opponentScore}}
-					}
-				}
-			}
-		}
-	}
-}
-
-func (h *GameHub) Close() {
-	for client := range h.clients {
-		h.closeClient(client)
-	}
-	close(h.receive)
-	close(h.register)
-	close(h.unregister)
-	for watcher := range h.watchers {
-		h.closeWatcher(watcher)
-	}
-	close(h.registerWatcher)
-	close(h.unregisterWatcher)
-}
-
-func (h *GameHub) closeClient(client *GameClient) {
-	delete(h.clients, client)
-	close(client.send)
-}
-
-func (h *GameHub) closeWatcher(watcher *GameWatcher) {
-	delete(h.watchers, watcher)
-	close(watcher.send)
-}
-
-type GameClient struct {
-	hub   *GameHub
-	conn  *websocket.Conn
-	send  chan *Message
-	score *int
-	code  string
-	team  string
-}
-
-type GameWatcher struct {
-	hub  *GameHub
-	conn *websocket.Conn
-	send chan *Message
-}
-
-// Receives messages from the client and sends them to the hub.
-func (c *GameClient) readPump() {
-	defer func() {
-		log.Printf("closing client")
-		c.hub.unregister <- c
-		c.conn.Close()
-	}()
-	c.conn.SetReadLimit(maxMessageSize)
-	c.conn.SetReadDeadline(time.Now().Add(pongWait))
-	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
-	for {
-		var message Message
-		err := c.conn.ReadJSON(&message)
-		if err != nil {
-			log.Printf("error: %v", err)
-			return
-		}
-		c.hub.receive <- &MessageWithClient{c, &message}
-	}
-}
-
-// Receives messages from the hub and sends them to the client.
-func (c *GameClient) writePump() {
-	ticker := time.NewTicker(pingPeriod)
-	defer func() {
-		ticker.Stop()
-		c.conn.Close()
-	}()
-	for {
-		select {
-		case message, ok := <-c.send:
-			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
-			if !ok {
-				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
-				return
-			}
-
-			err := c.conn.WriteJSON(message)
-			if err != nil {
-				return
-			}
-		case <-ticker.C:
-			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
-			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
-				return
-			}
-		}
-	}
-}
-
-// Receives messages from the client and sends them to the hub.
-func (c *GameWatcher) readPump() {
-	c.conn.SetReadLimit(maxMessageSize)
-	c.conn.SetReadDeadline(time.Now().Add(pongWait))
-	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
-}
-
-// Receives messages from the hub and sends them to the client.
-func (c *GameWatcher) writePump() {
-	ticker := time.NewTicker(pingPeriod)
-	defer func() {
-		ticker.Stop()
-		c.conn.Close()
-		log.Printf("closing watcher")
-		c.hub.unregisterWatcher <- c
-	}()
-	for {
-		select {
-		case message, ok := <-c.send:
-			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
-			if !ok {
-				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
-				return
-			}
-
-			err := c.conn.WriteJSON(message)
-			if err != nil {
-				return
-			}
-		case <-ticker.C:
-			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
-			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
-				return
-			}
-		}
-	}
-}
-
-type GameHubs struct {
-	hubs map[int]*GameHub
-}
-
-func NewGameHubs() *GameHubs {
-	return &GameHubs{
-		hubs: make(map[int]*GameHub),
-	}
-}
-
-func (hubs *GameHubs) Close() {
-	for _, hub := range hubs.hubs {
-		hub.Close()
-	}
-}
-
-func (hubs *GameHubs) RestoreFromDB(ctx context.Context, q *db.Queries) error {
-	games, err := q.ListGames(ctx)
-	if err != nil {
-		return err
-	}
-	_ = games
-	return nil
-}
-
-func (hubs *GameHubs) SockHandler() *sockHandler {
-	return newSockHandler(hubs)
-}
diff --git a/backend/game/http.go b/backend/game/http.go
index a5a7ded..beda46c 100644
--- a/backend/game/http.go
+++ b/backend/game/http.go
@@ -18,12 +18,13 @@ func newSockHandler(hubs *GameHubs) *sockHandler {
 }
 
 func (h *sockHandler) HandleSockGolfPlay(c echo.Context) error {
+	// TODO: auth
 	gameId := c.Param("gameId")
 	gameIdInt, err := strconv.Atoi(gameId)
 	if err != nil {
 		return echo.NewHTTPError(http.StatusBadRequest, "Invalid game id")
 	}
-	var foundHub *GameHub
+	var foundHub *gameHub
 	for _, hub := range h.hubs.hubs {
 		if hub.game.gameID == gameIdInt {
 			foundHub = hub
@@ -37,12 +38,13 @@ func (h *sockHandler) HandleSockGolfPlay(c echo.Context) error {
 }
 
 func (h *sockHandler) HandleSockGolfWatch(c echo.Context) error {
+	// TODO: auth
 	gameId := c.Param("gameId")
 	gameIdInt, err := strconv.Atoi(gameId)
 	if err != nil {
 		return echo.NewHTTPError(http.StatusBadRequest, "Invalid game id")
 	}
-	var foundHub *GameHub
+	var foundHub *gameHub
 	for _, hub := range h.hubs.hubs {
 		if hub.game.gameID == gameIdInt {
 			foundHub = hub
diff --git a/backend/game/hub.go b/backend/game/hub.go
new file mode 100644
index 0000000..c61f2bb
--- /dev/null
+++ b/backend/game/hub.go
@@ -0,0 +1,273 @@
+package game
+
+import (
+	"context"
+	"log"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgtype"
+
+	"github.com/nsfisis/iosdc-2024-albatross/backend/api"
+	"github.com/nsfisis/iosdc-2024-albatross/backend/db"
+)
+
+type playerClientState int
+
+const (
+	playerClientStateWaitingEntries playerClientState = iota
+	playerClientStateEntried
+	playerClientStateReady
+)
+
+type gameHub struct {
+	ctx               context.Context
+	game              *game
+	q                 *db.Queries
+	players           map[*playerClient]playerClientState
+	registerPlayer    chan *playerClient
+	unregisterPlayer  chan *playerClient
+	playerC2SMessages chan *playerMessageC2SWithClient
+	watchers          map[*watcherClient]bool
+	registerWatcher   chan *watcherClient
+	unregisterWatcher chan *watcherClient
+}
+
+func newGameHub(ctx context.Context, game *game, q *db.Queries) *gameHub {
+	return &gameHub{
+		ctx:               ctx,
+		game:              game,
+		q:                 q,
+		players:           make(map[*playerClient]playerClientState),
+		registerPlayer:    make(chan *playerClient),
+		unregisterPlayer:  make(chan *playerClient),
+		playerC2SMessages: make(chan *playerMessageC2SWithClient),
+		watchers:          make(map[*watcherClient]bool),
+		registerWatcher:   make(chan *watcherClient),
+		unregisterWatcher: make(chan *watcherClient),
+	}
+}
+
+func (hub *gameHub) run() {
+	ticker := time.NewTicker(10 * time.Second)
+	defer func() {
+		ticker.Stop()
+	}()
+
+	for {
+		select {
+		case player := <-hub.registerPlayer:
+			hub.players[player] = playerClientStateWaitingEntries
+		case player := <-hub.unregisterPlayer:
+			if _, ok := hub.players[player]; ok {
+				hub.closePlayerClient(player)
+			}
+		case watcher := <-hub.registerWatcher:
+			hub.watchers[watcher] = true
+		case watcher := <-hub.unregisterWatcher:
+			if _, ok := hub.watchers[watcher]; ok {
+				hub.closeWatcherClient(watcher)
+			}
+		case message := <-hub.playerC2SMessages:
+			switch msg := message.message.(type) {
+			case *playerMessageC2SEntry:
+				log.Printf("entry: %v", message.message)
+				// TODO: assert state is waiting_entries
+				hub.players[message.client] = playerClientStateEntried
+				entriedPlayerCount := 0
+				for _, state := range hub.players {
+					if playerClientStateEntried <= state {
+						entriedPlayerCount++
+					}
+				}
+				if entriedPlayerCount == 2 {
+					for player := range hub.players {
+						player.s2cMessages <- &playerMessageS2CPrepare{
+							Type: playerMessageTypeS2CPrepare,
+							Data: playerMessageS2CPreparePayload{
+								Problem: api.Problem{
+									ProblemId:   1,
+									Title:       "the answer",
+									Description: "print 42",
+								},
+							},
+						}
+					}
+					err := hub.q.UpdateGameState(hub.ctx, db.UpdateGameStateParams{
+						GameID: int32(hub.game.gameID),
+						State:  string(gameStatePrepare),
+					})
+					if err != nil {
+						log.Fatalf("failed to set game state: %v", err)
+					}
+					hub.game.state = gameStatePrepare
+				}
+			case *playerMessageC2SReady:
+				log.Printf("ready: %v", message.message)
+				// TODO: assert state is prepare
+				hub.players[message.client] = playerClientStateReady
+				readyPlayerCount := 0
+				for _, state := range hub.players {
+					if playerClientStateReady <= state {
+						readyPlayerCount++
+					}
+				}
+				if readyPlayerCount == 2 {
+					startAt := time.Now().Add(11 * time.Second).UTC()
+					for player := range hub.players {
+						player.s2cMessages <- &playerMessageS2CStart{
+							Type: playerMessageTypeS2CStart,
+							Data: playerMessageS2CStartPayload{
+								StartAt: int(startAt.Unix()),
+							},
+						}
+					}
+					err := hub.q.UpdateGameStartedAt(hub.ctx, db.UpdateGameStartedAtParams{
+						GameID: int32(hub.game.gameID),
+						StartedAt: pgtype.Timestamp{
+							Time:             startAt,
+							InfinityModifier: pgtype.Finite,
+							Valid:            true,
+						},
+					})
+					if err != nil {
+						log.Fatalf("failed to set game state: %v", err)
+					}
+					hub.game.startedAt = &startAt
+					err = hub.q.UpdateGameState(hub.ctx, db.UpdateGameStateParams{
+						GameID: int32(hub.game.gameID),
+						State:  string(gameStateStarting),
+					})
+					if err != nil {
+						log.Fatalf("failed to set game state: %v", err)
+					}
+					hub.game.state = gameStateStarting
+				}
+			case *playerMessageC2SCode:
+				// TODO: assert game state is gaming
+				log.Printf("code: %v", message.message)
+				code := msg.Data.Code
+				score := len(code)
+				message.client.s2cMessages <- &playerMessageS2CExecResult{
+					Type: playerMessageTypeS2CExecResult,
+					Data: playerMessageS2CExecResultPayload{
+						Score:  &score,
+						Status: api.Success,
+					},
+				}
+			default:
+				log.Fatalf("unexpected message type: %T", message.message)
+			}
+		case <-ticker.C:
+			if hub.game.state == gameStateStarting {
+				if time.Now().After(*hub.game.startedAt) {
+					err := hub.q.UpdateGameState(hub.ctx, db.UpdateGameStateParams{
+						GameID: int32(hub.game.gameID),
+						State:  string(gameStateGaming),
+					})
+					if err != nil {
+						log.Fatalf("failed to set game state: %v", err)
+					}
+					hub.game.state = gameStateGaming
+				}
+			} else if hub.game.state == gameStateGaming {
+				if time.Now().After(hub.game.startedAt.Add(time.Duration(hub.game.durationSeconds) * time.Second)) {
+					err := hub.q.UpdateGameState(hub.ctx, db.UpdateGameStateParams{
+						GameID: int32(hub.game.gameID),
+						State:  string(gameStateFinished),
+					})
+					if err != nil {
+						log.Fatalf("failed to set game state: %v", err)
+					}
+					hub.game.state = gameStateFinished
+				}
+				hub.close()
+				return
+			}
+		}
+	}
+}
+
+func (hub *gameHub) close() {
+	for client := range hub.players {
+		hub.closePlayerClient(client)
+	}
+	close(hub.registerPlayer)
+	close(hub.unregisterPlayer)
+	close(hub.playerC2SMessages)
+	for watcher := range hub.watchers {
+		hub.closeWatcherClient(watcher)
+	}
+	close(hub.registerWatcher)
+	close(hub.unregisterWatcher)
+}
+
+func (hub *gameHub) closePlayerClient(player *playerClient) {
+	delete(hub.players, player)
+	close(player.s2cMessages)
+}
+
+func (hub *gameHub) closeWatcherClient(watcher *watcherClient) {
+	delete(hub.watchers, watcher)
+	close(watcher.s2cMessages)
+}
+
+type GameHubs struct {
+	hubs map[int]*gameHub
+	q    *db.Queries
+}
+
+func NewGameHubs(q *db.Queries) *GameHubs {
+	return &GameHubs{
+		hubs: make(map[int]*gameHub),
+		q:    q,
+	}
+}
+
+func (hubs *GameHubs) Close() {
+	for _, hub := range hubs.hubs {
+		hub.close()
+	}
+}
+
+func (hubs *GameHubs) RestoreFromDB(ctx context.Context) error {
+	games, err := hubs.q.ListGames(ctx)
+	if err != nil {
+		return err
+	}
+	for _, row := range games {
+		var startedAt *time.Time
+		if row.StartedAt.Valid {
+			startedAt = &row.StartedAt.Time
+		}
+		var problem_ *problem
+		if row.ProblemID.Valid {
+			if !row.Title.Valid || !row.Description.Valid {
+				panic("inconsistent data")
+			}
+			problem_ = &problem{
+				problemID:   int(row.ProblemID.Int32),
+				title:       row.Title.String,
+				description: row.Description.String,
+			}
+		}
+		hubs.hubs[int(row.GameID)] = newGameHub(ctx, &game{
+			gameID:          int(row.GameID),
+			durationSeconds: int(row.DurationSeconds),
+			state:           gameState(row.State),
+			displayName:     row.DisplayName,
+			startedAt:       startedAt,
+			problem:         problem_,
+		}, hubs.q)
+	}
+	return nil
+}
+
+func (hubs *GameHubs) Run() {
+	for _, hub := range hubs.hubs {
+		go hub.run()
+	}
+}
+
+func (hubs *GameHubs) SockHandler() *sockHandler {
+	return newSockHandler(hubs)
+}
diff --git a/backend/game/message.go b/backend/game/message.go
index 7d1a166..9116bde 100644
--- a/backend/game/message.go
+++ b/backend/game/message.go
@@ -3,102 +3,67 @@ package game
 import (
 	"encoding/json"
 	"fmt"
-)
-
-type MessageWithClient struct {
-	Client  *GameClient
-	Message *Message
-}
-
-type Message struct {
-	Type string      `json:"type"`
-	Data MessageData `json:"data"`
-}
-
-type MessageData interface{}
-
-type MessageDataConnect struct {
-}
-
-type MessageDataPrepare struct {
-	Problem string `json:"problem"`
-}
-
-type MessageDataReady struct {
-}
 
-type MessageDataStart struct {
-	StartTime string `json:"startTime"`
-}
-
-type MessageDataCode struct {
-	Code string `json:"code"`
-}
-
-type MessageDataScore struct {
-	Score int `json:"score"`
-}
+	"github.com/nsfisis/iosdc-2024-albatross/backend/api"
+)
 
-type MessageDataFinish struct {
-	YourScore     *int `json:"yourScore"`
-	OpponentScore *int `json:"opponentScore"`
-}
+const (
+	playerMessageTypeS2CPrepare    = "player:s2c:prepare"
+	playerMessageTypeS2CStart      = "player:s2c:start"
+	playerMessageTypeS2CExecResult = "player:s2c:execreslut"
+	playerMessageTypeC2SEntry      = "player:c2s:entry"
+	playerMessageTypeC2SReady      = "player:c2s:ready"
+	playerMessageTypeC2SCode       = "player:c2s:code"
+)
 
-type MessageDataWatch struct {
-	Problem string `json:"problem"`
-	ScoreA  *int   `json:"scoreA"`
-	CodeA   string `json:"codeA"`
-	ScoreB  *int   `json:"scoreB"`
-	CodeB   string `json:"codeB"`
+type playerMessageC2SWithClient struct {
+	client  *playerClient
+	message playerMessageC2S
 }
 
-func (m *Message) UnmarshalJSON(data []byte) error {
-	var raw map[string]json.RawMessage
-	if err := json.Unmarshal(data, &raw); err != nil {
-		return err
-	}
-
-	if err := json.Unmarshal(raw["type"], &m.Type); err != nil {
-		return err
+type playerMessage = api.GamePlayerMessage
+
+type playerMessageS2C = interface{}
+type playerMessageS2CPrepare = api.GamePlayerMessageS2CPrepare
+type playerMessageS2CPreparePayload = api.GamePlayerMessageS2CPreparePayload
+type playerMessageS2CStart = api.GamePlayerMessageS2CStart
+type playerMessageS2CStartPayload = api.GamePlayerMessageS2CStartPayload
+type playerMessageS2CExecResult = api.GamePlayerMessageS2CExecResult
+type playerMessageS2CExecResultPayload = api.GamePlayerMessageS2CExecResultPayload
+
+type playerMessageC2S = interface{}
+type playerMessageC2SEntry = api.GamePlayerMessageC2SEntry
+type playerMessageC2SReady = api.GamePlayerMessageC2SReady
+type playerMessageC2SCode = api.GamePlayerMessageC2SCode
+type playerMessageC2SCodePayload = api.GamePlayerMessageC2SCodePayload
+
+func asPlayerMessageC2S(raw map[string]json.RawMessage) (playerMessageC2S, error) {
+	var typ string
+	if err := json.Unmarshal(raw["type"], &typ); err != nil {
+		return nil, err
 	}
 
-	var err error
-	switch m.Type {
-	case "connect":
-		var data MessageDataConnect
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
-	case "prepare":
-		var data MessageDataPrepare
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
-	case "ready":
-		var data MessageDataReady
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
-	case "start":
-		var data MessageDataStart
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
-	case "code":
-		var data MessageDataCode
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
-	case "score":
-		var data MessageDataScore
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
-	case "finish":
-		var data MessageDataFinish
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
-	case "watch":
-		var data MessageDataWatch
-		err = json.Unmarshal(raw["data"], &data)
-		m.Data = data
+	switch typ {
+	case playerMessageTypeC2SEntry:
+		return &playerMessageC2SEntry{
+			Type: playerMessageTypeC2SEntry,
+		}, nil
+	case playerMessageTypeC2SReady:
+		return &playerMessageC2SReady{
+			Type: playerMessageTypeC2SReady,
+		}, nil
+	case playerMessageTypeC2SCode:
+		var payload playerMessageC2SCodePayload
+		if err := json.Unmarshal(raw["data"], &payload); err != nil {
+			return nil, err
+		}
+		return &playerMessageC2SCode{
+			Type: playerMessageTypeC2SCode,
+			Data: payload,
+		}, nil
 	default:
-		err = fmt.Errorf("unknown message type: %s", m.Type)
+		return nil, fmt.Errorf("unknown message type: %s", typ)
 	}
-
-	return err
 }
+
+type watcherMessageS2C = interface{}
diff --git a/backend/game/models.go b/backend/game/models.go
new file mode 100644
index 0000000..4e9ee87
--- /dev/null
+++ b/backend/game/models.go
@@ -0,0 +1,34 @@
+package game
+
+import (
+	"time"
+
+	"github.com/nsfisis/iosdc-2024-albatross/backend/api"
+)
+
+type gameState = api.GameState
+
+const (
+	gameStateClosed         gameState = api.Closed
+	gameStateWaitingEntries gameState = api.WaitingEntries
+	gameStateWaitingStart   gameState = api.WaitingStart
+	gameStatePrepare        gameState = api.Prepare
+	gameStateStarting       gameState = api.Starting
+	gameStateGaming         gameState = api.Gaming
+	gameStateFinished       gameState = api.Finished
+)
+
+type game struct {
+	gameID          int
+	state           gameState
+	displayName     string
+	durationSeconds int
+	startedAt       *time.Time
+	problem         *problem
+}
+
+type problem struct {
+	problemID   int
+	title       string
+	description string
+}
diff --git a/backend/game/ws.go b/backend/game/ws.go
index 2ed17af..013db7a 100644
--- a/backend/game/ws.go
+++ b/backend/game/ws.go
@@ -17,28 +17,40 @@ const (
 var upgrader = websocket.Upgrader{
 	ReadBufferSize:  1024,
 	WriteBufferSize: 1024,
+	CheckOrigin: func(r *http.Request) bool {
+		// TODO: insecure!
+		return true
+	},
 }
 
-func servePlayerWs(hub *GameHub, w http.ResponseWriter, r *http.Request, team string) error {
+func servePlayerWs(hub *gameHub, w http.ResponseWriter, r *http.Request, team string) error {
 	conn, err := upgrader.Upgrade(w, r, nil)
 	if err != nil {
 		return err
 	}
-	client := &GameClient{hub: hub, conn: conn, send: make(chan *Message), team: team}
-	client.hub.register <- client
+	player := &playerClient{
+		hub:         hub,
+		conn:        conn,
+		s2cMessages: make(chan playerMessageS2C),
+	}
+	hub.registerPlayer <- player
 
-	go client.writePump()
-	go client.readPump()
+	go player.writePump()
+	go player.readPump()
 	return nil
 }
 
-func serveWatcherWs(hub *GameHub, w http.ResponseWriter, r *http.Request) error {
+func serveWatcherWs(hub *gameHub, w http.ResponseWriter, r *http.Request) error {
 	conn, err := upgrader.Upgrade(w, r, nil)
 	if err != nil {
 		return err
 	}
-	watcher := &GameWatcher{hub: hub, conn: conn, send: make(chan *Message)}
-	watcher.hub.registerWatcher <- watcher
+	watcher := &watcherClient{
+		hub:         hub,
+		conn:        conn,
+		s2cMessages: make(chan watcherMessageS2C),
+	}
+	hub.registerWatcher <- watcher
 
 	go watcher.writePump()
 	go watcher.readPump()
diff --git a/backend/main.go b/backend/main.go
index 379fe8d..91caa73 100644
--- a/backend/main.go
+++ b/backend/main.go
@@ -6,7 +6,7 @@ import (
 	"log"
 	"net/http"
 
-	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/labstack/echo/v4"
 	"github.com/labstack/echo/v4/middleware"
 	oapimiddleware "github.com/oapi-codegen/echo-middleware"
@@ -16,6 +16,19 @@ import (
 	"github.com/nsfisis/iosdc-2024-albatross/backend/game"
 )
 
+func connectDB(ctx context.Context, dsn string) (*pgxpool.Pool, error) {
+	pool, err := pgxpool.New(ctx, dsn)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := pool.Ping(ctx); err != nil {
+		return nil, err
+	}
+
+	return pool, nil
+}
+
 func main() {
 	var err error
 	config, err := NewConfigFromEnv()
@@ -30,13 +43,14 @@ func main() {
 
 	ctx := context.Background()
 
-	conn, err := pgx.Connect(ctx, fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=disable", config.dbHost, config.dbPort, config.dbUser, config.dbPassword, config.dbName))
+	dbDSN := fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=disable", config.dbHost, config.dbPort, config.dbUser, config.dbPassword, config.dbName)
+	connPool, err := connectDB(ctx, dbDSN)
 	if err != nil {
 		log.Fatalf("Error connecting to db %v", err)
 	}
-	defer conn.Close(ctx)
+	defer connPool.Close()
 
-	queries := db.New(conn)
+	queries := db.New(connPool)
 
 	e := echo.New()
 
@@ -50,20 +64,22 @@ func main() {
 		api.NewJWTMiddleware(),
 	}))
 
-	gameHubs := game.NewGameHubs()
-	err = gameHubs.RestoreFromDB(ctx, queries)
+	gameHubs := game.NewGameHubs(queries)
+	err = gameHubs.RestoreFromDB(ctx)
 	if err != nil {
 		log.Fatalf("Error restoring game hubs from db %v", err)
 	}
 	defer gameHubs.Close()
 	sockGroup := e.Group("/sock")
 	sockHandler := gameHubs.SockHandler()
-	sockGroup.GET("/golf/:gameId/watch", func(c echo.Context) error {
-		return sockHandler.HandleSockGolfWatch(c)
-	})
 	sockGroup.GET("/golf/:gameId/play", func(c echo.Context) error {
 		return sockHandler.HandleSockGolfPlay(c)
 	})
+	sockGroup.GET("/golf/:gameId/watch", func(c echo.Context) error {
+		return sockHandler.HandleSockGolfWatch(c)
+	})
+
+	gameHubs.Run()
 
 	if err := e.Start(":80"); err != http.ErrServerClosed {
 		log.Fatal(err)
diff --git a/backend/query.sql b/backend/query.sql
index 9b038a5..b2ad2c4 100644
--- a/backend/query.sql
+++ b/backend/query.sql
@@ -18,3 +18,19 @@ SELECT * FROM games
 LEFT JOIN problems ON games.problem_id = problems.problem_id
 JOIN game_players ON games.game_id = game_players.game_id
 WHERE game_players.user_id = $1;
+
+-- name: UpdateGameState :exec
+UPDATE games
+SET state = $2
+WHERE game_id = $1;
+
+-- name: UpdateGameStartedAt :exec
+UPDATE games
+SET started_at = $2
+WHERE game_id = $1;
+
+-- name: GetGameById :one
+SELECT * FROM games
+LEFT JOIN problems ON games.problem_id = problems.problem_id
+WHERE games.game_id = $1
+LIMIT 1;
diff --git a/frontend/app/.server/api/schema.d.ts b/frontend/app/.server/api/schema.d.ts
index cd87705..40a3347 100644
--- a/frontend/app/.server/api/schema.d.ts
+++ b/frontend/app/.server/api/schema.d.ts
@@ -118,6 +118,58 @@ export interface paths {
         patch?: never;
         trace?: never;
     };
+    [path: `/games/${integer}`]: {
+        parameters: {
+            query?: never;
+            header?: never;
+            path?: never;
+            cookie?: never;
+        };
+        /** Get a game */
+        get: {
+            parameters: {
+                query?: never;
+                header: {
+                    Authorization: string;
+                };
+                path: {
+                    game_id: number;
+                };
+                cookie?: never;
+            };
+            requestBody?: never;
+            responses: {
+                /** @description A game */
+                200: {
+                    headers: {
+                        [name: string]: unknown;
+                    };
+                    content: {
+                        "application/json": components["schemas"]["Game"];
+                    };
+                };
+                /** @description Forbidden */
+                403: {
+                    headers: {
+                        [name: string]: unknown;
+                    };
+                    content: {
+                        "application/json": {
+                            /** @example Forbidden operation */
+                            message: string;
+                        };
+                    };
+                };
+            };
+        };
+        put?: never;
+        post?: never;
+        delete?: never;
+        options?: never;
+        head?: never;
+        patch?: never;
+        trace?: never;
+    };
 }
 export type webhooks = Record<string, never>;
 export interface components {
@@ -138,7 +190,7 @@ export interface components {
             /** @example 1 */
             game_id: number;
             /**
-             * @example active
+             * @example closed
              * @enum {string}
              */
             state: "closed" | "waiting_entries" | "waiting_start" | "prepare" | "starting" | "gaming" | "finished";
@@ -158,6 +210,57 @@ export interface components {
             /** @example This is a problem */
             description: string;
         };
+        GamePlayerMessage: components["schemas"]["GamePlayerMessageS2C"] | components["schemas"]["GamePlayerMessageC2S"];
+        GamePlayerMessageS2C: components["schemas"]["GamePlayerMessageS2CPrepare"] | components["schemas"]["GamePlayerMessageS2CStart"] | components["schemas"]["GamePlayerMessageS2CExecResult"];
+        GamePlayerMessageS2CPrepare: {
+            /** @constant */
+            type: "player:s2c:prepare";
+            data: components["schemas"]["GamePlayerMessageS2CPreparePayload"];
+        };
+        GamePlayerMessageS2CPreparePayload: {
+            problem: components["schemas"]["Problem"];
+        };
+        GamePlayerMessageS2CStart: {
+            /** @constant */
+            type: "player:s2c:start";
+            data: components["schemas"]["GamePlayerMessageS2CStartPayload"];
+        };
+        GamePlayerMessageS2CStartPayload: {
+            /** @example 946684800 */
+            start_at: number;
+        };
+        GamePlayerMessageS2CExecResult: {
+            /** @constant */
+            type: "player:s2c:execresult";
+            data: components["schemas"]["GamePlayerMessageS2CExecResultPayload"];
+        };
+        GamePlayerMessageS2CExecResultPayload: {
+            /**
+             * @example success
+             * @enum {string}
+             */
+            status: "success";
+            /** @example 100 */
+            score: number | null;
+        };
+        GamePlayerMessageC2S: components["schemas"]["GamePlayerMessageC2SEntry"] | components["schemas"]["GamePlayerMessageC2SReady"] | components["schemas"]["GamePlayerMessageC2SCode"];
+        GamePlayerMessageC2SEntry: {
+            /** @constant */
+            type: "player:c2s:entry";
+        };
+        GamePlayerMessageC2SReady: {
+            /** @constant */
+            type: "player:c2s:ready";
+        };
+        GamePlayerMessageC2SCode: {
+            /** @constant */
+            type: "player:c2s:code";
+            data: components["schemas"]["GamePlayerMessageC2SCodePayload"];
+        };
+        GamePlayerMessageC2SCodePayload: {
+            /** @example print('Hello, world!') */
+            code: string;
+        };
     };
     responses: never;
     parameters: never;
diff --git a/frontend/app/components/GolfPlayApp.tsx b/frontend/app/components/GolfPlayApp.tsx
new file mode 100644
index 0000000..c6c20d4
--- /dev/null
+++ b/frontend/app/components/GolfPlayApp.tsx
@@ -0,0 +1,146 @@
+import type { components } from "../.server/api/schema";
+import { useState, useEffect } from "react";
+import useWebSocket, { ReadyState } from "react-use-websocket";
+import { useDebouncedCallback } from "use-debounce";
+import GolfPlayAppConnecting from "./GolfPlayApps/GolfPlayAppConnecting";
+import GolfPlayAppWaiting from "./GolfPlayApps/GolfPlayAppWaiting";
+import GolfPlayAppStarting from "./GolfPlayApps/GolfPlayAppStarting";
+import GolfPlayAppGaming from "./GolfPlayApps/GolfPlayAppGaming";
+import GolfPlayAppFinished from "./GolfPlayApps/GolfPlayAppFinished";
+
+type WebSocketMessage = components["schemas"]["GamePlayerMessageS2C"];
+
+type Game = components["schemas"]["Game"];
+type Problem = components["schemas"]["Problem"];
+
+type GameState = "connecting" | "waiting" | "starting" | "gaming" | "finished";
+
+export default function GolfPlayApp({ game }: { game: Game }) {
+  // const socketUrl = `wss://t.nil.ninja/iosdc/2024/sock/golf/${game.game_id}/play`;
+  const socketUrl =
+    process.env.NODE_ENV === "development"
+      ? `ws://localhost:8002/sock/golf/${game.game_id}/play`
+      : `ws://api-server/sock/golf/${game.game_id}/play`;
+
+  const { sendJsonMessage, lastJsonMessage, readyState } =
+    useWebSocket<WebSocketMessage>(socketUrl, {});
+
+  const [gameState, setGameState] = useState<GameState>("connecting");
+
+  const [problem, setProblem] = useState<Problem | null>(null);
+
+  const [startedAt, setStartedAt] = useState<number | null>(null);
+
+  const [timeLeftSeconds, setTimeLeftSeconds] = useState<number | null>(null);
+
+  useEffect(() => {
+    if (gameState === "starting" && startedAt !== null) {
+      const timer1 = setInterval(() => {
+        setTimeLeftSeconds((prev) => {
+          if (prev === null) {
+            return null;
+          }
+          if (prev <= 1) {
+            clearInterval(timer1);
+            setGameState("gaming");
+            return 0;
+          }
+          return prev - 1;
+        });
+      }, 1000);
+
+      const timer2 = setInterval(() => {
+        const nowSec = Math.floor(Date.now() / 1000);
+        const finishedAt = startedAt + game.duration_seconds;
+        if (nowSec >= finishedAt) {
+          clearInterval(timer2);
+          setGameState("finished");
+        }
+      }, 1000);
+
+      return () => {
+        clearInterval(timer1);
+        clearInterval(timer2);
+      };
+    }
+  }, [gameState, startedAt, game.duration_seconds]);
+
+  const [currentScore, setCurrentScore] = useState<number | null>(null);
+  void setCurrentScore;
+
+  const onCodeChange = useDebouncedCallback((code: string) => {
+    console.log("player:c2s:code");
+    sendJsonMessage({
+      type: "player:c2s:code",
+      data: { code },
+    });
+  }, 1000);
+
+  if (readyState === ReadyState.UNINSTANTIATED) {
+    throw new Error("WebSocket is not connected");
+  }
+
+  useEffect(() => {
+    if (readyState === ReadyState.CLOSING || readyState === ReadyState.CLOSED) {
+      if (gameState !== "finished") {
+        setGameState("connecting");
+      }
+    } else if (readyState === ReadyState.CONNECTING) {
+      setGameState("connecting");
+    } else if (readyState === ReadyState.OPEN) {
+      if (lastJsonMessage !== null) {
+        console.log(lastJsonMessage.type);
+        if (lastJsonMessage.type === "player:s2c:prepare") {
+          const { problem } = lastJsonMessage.data;
+          setProblem(problem);
+          console.log("player:c2s:ready");
+          sendJsonMessage({ type: "player:c2s:ready" });
+        } else if (lastJsonMessage.type === "player:s2c:start") {
+          if (
+            gameState !== "starting" &&
+            gameState !== "gaming" &&
+            gameState !== "finished"
+          ) {
+            const { start_at } = lastJsonMessage.data;
+            setStartedAt(start_at);
+            const nowSec = Math.floor(Date.now() / 1000);
+            setTimeLeftSeconds(start_at - nowSec);
+            setGameState("starting");
+          }
+        } else if (lastJsonMessage.type === "player:s2c:execresult") {
+          const { score } = lastJsonMessage.data;
+          if (
+            score !== null &&
+            (currentScore === null || score < currentScore)
+          ) {
+            setCurrentScore(score);
+          }
+        }
+      } else {
+        setGameState("waiting");
+        console.log("player:c2s:entry");
+        sendJsonMessage({ type: "player:c2s:entry" });
+      }
+    }
+  }, [sendJsonMessage, lastJsonMessage, readyState, gameState, currentScore]);
+
+  if (gameState === "connecting") {
+    return <GolfPlayAppConnecting />;
+  } else if (gameState === "waiting") {
+    return <GolfPlayAppWaiting />;
+  } else if (gameState === "starting") {
+    return <GolfPlayAppStarting timeLeft={timeLeftSeconds!} />;
+  } else if (gameState === "gaming") {
+    return (
+      <GolfPlayAppGaming
+        problem={problem!.description}
+        onCodeChange={onCodeChange}
+        currentScore={currentScore}
+      />
+    );
+  } else if (gameState === "finished") {
+    return <GolfPlayAppFinished />;
+  } else {
+    return null;
+  }
+}
diff --git a/frontend/app/components/GolfPlayApps/GolfPlayAppConnecting.tsx b/frontend/app/components/GolfPlayApps/GolfPlayAppConnecting.tsx
new file mode 100644
index 0000000..e92a8e0
--- /dev/null
+++ b/frontend/app/components/GolfPlayApps/GolfPlayAppConnecting.tsx
@@ -0,0 +1,3 @@
+export default function GolfPlayAppConnecting() {
+  return <div>Connecting...</div>;
+}
diff --git a/frontend/app/components/GolfPlayApps/GolfPlayAppFinished.tsx b/frontend/app/components/GolfPlayApps/GolfPlayAppFinished.tsx
new file mode 100644
index 0000000..75ceb71
--- /dev/null
+++ b/frontend/app/components/GolfPlayApps/GolfPlayAppFinished.tsx
@@ -0,0 +1,3 @@
+export default function GolfPlayAppFinished() {
+  return <div>Finished</div>;
+}
diff --git a/frontend/app/components/GolfPlayApps/GolfPlayAppGaming.tsx b/frontend/app/components/GolfPlayApps/GolfPlayAppGaming.tsx
new file mode 100644
index 0000000..332cb3c
--- /dev/null
+++ b/frontend/app/components/GolfPlayApps/GolfPlayAppGaming.tsx
@@ -0,0 +1,30 @@
+export default function GolfPlayAppGaming({
+  problem,
+  onCodeChange,
+  currentScore,
+}: {
+  problem: string;
+  onCodeChange: (code: string) => void;
+  currentScore: number | null;
+}) {
+  const handleTextChange = (e: React.ChangeEvent<HTMLTextAreaElement>) => {
+    onCodeChange(e.target.value);
+  };
+
+  return (
+    <div style={{ display: "flex" }}>
+      <div style={{ flex: 1, padding: "10px", borderRight: "1px solid #ccc" }}>
+        <div>{problem}</div>
+        <div>
+          {currentScore == null ? "Score: -" : `Score: ${currentScore}`}
+        </div>
+      </div>
+      <div style={{ flex: 1, padding: "10px" }}>
+        <textarea
+          style={{ width: "100%", height: "100%" }}
+          onChange={handleTextChange}
+        />
+      </div>
+    </div>
+  );
+}
diff --git a/frontend/app/components/GolfPlayApps/GolfPlayAppStarting.tsx b/frontend/app/components/GolfPlayApps/GolfPlayAppStarting.tsx
new file mode 100644
index 0000000..bf45abb
--- /dev/null
+++ b/frontend/app/components/GolfPlayApps/GolfPlayAppStarting.tsx
@@ -0,0 +1,7 @@
+export default function GolfPlayAppStarting({
+  timeLeft,
+}: {
+  timeLeft: number;
+}) {
+  return <div>Starting... ({timeLeft} s)</div>;
+}
diff --git a/frontend/app/components/GolfPlayApps/GolfPlayAppWaiting.tsx b/frontend/app/components/GolfPlayApps/GolfPlayAppWaiting.tsx
new file mode 100644
index 0000000..a0751e0
--- /dev/null
+++ b/frontend/app/components/GolfPlayApps/GolfPlayAppWaiting.tsx
@@ -0,0 +1,3 @@
+export default function GolfPlayAppWaiting() {
+  return <div>Waiting...</div>;
+}
diff --git a/frontend/app/routes/golf.$gameId.play.tsx b/frontend/app/routes/golf.$gameId.play.tsx
new file mode 100644
index 0000000..bda563f
--- /dev/null
+++ b/frontend/app/routes/golf.$gameId.play.tsx
@@ -0,0 +1,33 @@
+import type { LoaderFunctionArgs } from "@remix-run/node";
+import { isAuthenticated } from "../.server/auth";
+import { apiClient } from "../.server/api/client";
+import { useLoaderData } from "@remix-run/react";
+import GolfPlayApp from "../components/GolfPlayApp";
+
+export async function loader({ params, request }: LoaderFunctionArgs) {
+  const { token } = await isAuthenticated(request, {
+    failureRedirect: "/login",
+  });
+  const { data, error } = await apiClient.GET("/games/{game_id}", {
+    params: {
+      path: {
+        game_id: Number(params.gameId),
+      },
+      header: {
+        Authorization: `Bearer ${token}`,
+      },
+    },
+  });
+  if (error) {
+    throw new Error(error.message);
+  }
+  return {
+    game: data,
+  };
+}
+
+export default function GolfPlay() {
+  const { game } = useLoaderData<typeof loader>();
+
+  return <GolfPlayApp game={game} />;
+}
diff --git a/openapi.yaml b/openapi.yaml
index 002b229..d058381 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -87,6 +87,39 @@ paths:
                     example: "Forbidden operation"
                 required:
                   - message
+  /games/{game_id}:
+    get:
+      summary: Get a game
+      parameters:
+        - in: path
+          name: game_id
+          schema:
+            type: integer
+          required: true
+        - in: header
+          name: Authorization
+          schema:
+            type: string
+          required: true
+      responses:
+        '200':
+          description: A game
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Game'
+        '403':
+          description: Forbidden
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  message:
+                    type: string
+                    example: "Forbidden operation"
+                required:
+                  - message
 components:
   schemas:
     JwtPayload:
@@ -120,7 +153,7 @@ components:
           example: 1
         state:
           type: string
-          example: "active"
+          example: "closed"
           enum:
             - closed
             - waiting_entries
@@ -161,3 +194,123 @@ components:
         - problem_id
         - title
         - description
+    GamePlayerMessage:
+      oneOf:
+        - $ref: '#/components/schemas/GamePlayerMessageS2C'
+        - $ref: '#/components/schemas/GamePlayerMessageC2S'
+    GamePlayerMessageS2C:
+      oneOf:
+        - $ref: '#/components/schemas/GamePlayerMessageS2CPrepare'
+        - $ref: '#/components/schemas/GamePlayerMessageS2CStart'
+        - $ref: '#/components/schemas/GamePlayerMessageS2CExecResult'
+    GamePlayerMessageS2CPrepare:
+      type: object
+      properties:
+        type:
+          type: string
+          const: "player:s2c:prepare"
+        data:
+          $ref: '#/components/schemas/GamePlayerMessageS2CPreparePayload'
+      required:
+        - type
+        - data
+    GamePlayerMessageS2CPreparePayload:
+      type: object
+      properties:
+        problem:
+          $ref: '#/components/schemas/Problem'
+      required:
+        - problem
+    GamePlayerMessageS2CStart:
+      type: object
+      properties:
+        type:
+          type: string
+          const: "player:s2c:start"
+        data:
+          $ref: '#/components/schemas/GamePlayerMessageS2CStartPayload'
+      required:
+        - type
+        - data
+    GamePlayerMessageS2CStartPayload:
+      type: object
+      properties:
+        start_at:
+          type: integer
+          example: 946684800
+      required:
+        - start_at
+    GamePlayerMessageS2CExecResult:
+      type: object
+      properties:
+        type:
+          type: string
+          const: "player:s2c:execresult"
+        data:
+          $ref: '#/components/schemas/GamePlayerMessageS2CExecResultPayload'
+      required:
+        - type
+        - data
+    GamePlayerMessageS2CExecResultPayload:
+      type: object
+      properties:
+        status:
+          type: string
+          example: "success"
+          enum:
+            - success
+        score:
+          type: integer
+          nullable: true
+          example: 100
+      required:
+        - status
+        - score
+    GamePlayerMessageC2S:
+      oneOf:
+        - $ref: '#/components/schemas/GamePlayerMessageC2SEntry'
+        - $ref: '#/components/schemas/GamePlayerMessageC2SReady'
+        - $ref: '#/components/schemas/GamePlayerMessageC2SCode'
+    GamePlayerMessageC2SEntry:
+      type: object
+      properties:
+        type:
+          type: string
+          const: "player:c2s:entry"
+      required:
+        - type
+    GamePlayerMessageC2SReady:
+      type: object
+      properties:
+        type:
+          type: string
+          const: "player:c2s:ready"
+      required:
+        - type
+    GamePlayerMessageC2SCode:
+      type: object
+      properties:
+        type:
+          type: string
+          const: "player:c2s:code"
+        data:
+          $ref: '#/components/schemas/GamePlayerMessageC2SCodePayload'
+      required:
+        - type
+        - data
+    GamePlayerMessageC2SCodePayload:
+      type: object
+      properties:
+        code:
+          type: string
+          example: "print('Hello, world!')"
+      required:
+        - code
+    # GameWatcherMessage:
+    #   oneOf:
+    #     - $ref: '#/components/schemas/GameWatcherMessageS2C'
+    #     - $ref: '#/components/schemas/GameWatcherMessageC2S'
+    # GameWatcherMessageS2C:
+    #   oneOf:
+    # GameWatcherMessageC2S:
+    #   oneOf: