another fix

Arch/ThreadManager.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading;
 using GameServer.Game;
 using GameServer.Management;
@@ -59,8 +60,8 @@ namespace GameServer.Arch {
         }
 
         private static void Tick() {
-            foreach (var room in Server.Rooms.Values) {
+            foreach (var room in Server.Rooms.Values.Where(room => room.Game != null && room.Game.IsRunning)) {
-                room.Game?.Update();
+                room.Game.Update();
             }
             
             UpdateMain();

Game/GameManager.cs

@@ -7,6 +7,8 @@ namespace GameServer.Game {
         private Room Room { get; }
 
         private Dictionary<int, Player> Players { get; } = new();
+        
+        public bool IsRunning { get; set; }
 
         public GameManager(Room room) {
             Room = room;
@@ -17,10 +19,12 @@ namespace GameServer.Game {
             Start();
         }
 
-        public void Start() {
+        private void Start() {
             foreach (var player in Players.Values) {
                 player.Start();
             }
+            
+            IsRunning = true;
         }
 
         public void Update() {