Guide: Making A Turn-Based Or Card Game Multiplayer

extends SummerPlayer

func _ready() -> void:
    set_synced("hand_count", 0)
    set_synced("mana", 0)
    set_synced("ready", false)

extends SummerGame

var _turn_order: Array = []
var _active_turn_index := 0
var _board_state := {}

func _game_init() -> void:
    _board_state = {"round": 1, "stack_size": 0}

func _player_joined(player) -> void:
    _turn_order.append(player)
    player.set_synced("hand_count", 5)
    player.set_synced("mana", 1)
    _sync_turn_state()

func _player_left(player) -> void:
    _turn_order.erase(player)
    _active_turn_index = clamp(_active_turn_index, 0, max(_turn_order.size() - 1, 0))
    _sync_turn_state()

func end_turn(player) -> void:
    if not Summer.is_server():
        return
    if _turn_order.is_empty():
        return

    var active = _turn_order[_active_turn_index]
    if player != active:
        return

    _active_turn_index = (_active_turn_index + 1) % _turn_order.size()
    _board_state["round"] = int(_board_state.get("round", 1)) + 1
    _sync_turn_state()

func _sync_turn_state() -> void:
    for i in _turn_order.size():
        var p = _turn_order[i]
        p.set_synced("turn_active", i == _active_turn_index)
        p.set_synced("round", _board_state.get("round", 1))

func play_card(player, card_id: String, target_id: String) -> void:
    if not Summer.is_server():
        return
    if _turn_order[_active_turn_index] != player:
        return
    if not _is_legal_card_play(player, card_id, target_id):
        return

    _apply_card_effect(player, card_id, target_id)
    _sync_turn_state()