diff --git a/src/CommandHandlers/GauntletHandlers.cs b/src/CommandHandlers/GauntletHandlers.cs
index 7c4ea9a..d337159 100644
--- a/src/CommandHandlers/GauntletHandlers.cs
+++ b/src/CommandHandlers/GauntletHandlers.cs
@@ -30,7 +30,7 @@ class GauntletJoinRoomHandler : ICommandHandler
 class GauntletPlayAgainHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) {
-        GauntletRoom room = client.Room as GauntletRoom;
+        GauntletRoom room = (client.Room as GauntletRoom)!;
         room.SetPlayerReady(client, false);
 
         NetworkPacket packet = Utils.ArrNetworkPacket(new string[] {
@@ -52,7 +52,7 @@ class GauntletPlayAgainHandler : ICommandHandler
 class GauntletLobbyUserReadyHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) {
-        GauntletRoom room = client.Room as GauntletRoom;
+        GauntletRoom room = (client.Room as GauntletRoom)!;
         room.SetPlayerReady(client);
 
         NetworkPacket packet = Utils.ArrNetworkPacket(new string[] {
@@ -84,7 +84,7 @@ class GauntletLobbyUserReadyHandler : ICommandHandler
 class GauntletLobbyUserNotReadyHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) {
-        GauntletRoom room = client.Room as GauntletRoom;
+        GauntletRoom room = (client.Room as GauntletRoom)!;
         room.SetPlayerReady(client, false);
 
         NetworkPacket packet = Utils.ArrNetworkPacket(new string[] {
@@ -104,7 +104,7 @@ class GauntletLobbyUserNotReadyHandler : ICommandHandler
 class GauntletLevelLoadHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) { // {"a":13,"c":1,"p":{"c":"gs.GLL","p":{"0":"0","1":"0","2":"5","en":"GauntletGameExtension"},"r":365587}}
-        GauntletRoom room = client.Room as GauntletRoom;
+        GauntletRoom room = (client.Room as GauntletRoom)!;
         NetworkObject p = receivedObject.Get<NetworkObject>("p");
         
         NetworkPacket packet = Utils.ArrNetworkPacket(new string[] {
@@ -125,12 +125,12 @@ class GauntletLevelLoadHandler : ICommandHandler
 [ExtensionCommandHandler("gs.GLLD")]
 class GauntletLevelLoadedHandler : ICommandHandler
 {
-    private System.Timers.Timer timer = null;
+    private System.Timers.Timer? timer = null;
     private int counter;
     private GauntletRoom room;
 
     public void Handle(Client client, NetworkObject receivedObject) {
-        room = client.Room as GauntletRoom;
+        room = (client.Room as GauntletRoom)!;
         counter = 5;
         
         // {"a":13,"c":1,"p":{"c":"msg","p":{"arr":["GCDS","365587","4"]},"r":365587}}
@@ -149,7 +149,7 @@ class GauntletLevelLoadedHandler : ICommandHandler
         timer.Elapsed += OnTick;
     }
 
-    private void OnTick(Object source, ElapsedEventArgs e) {
+    private void OnTick(Object? source, ElapsedEventArgs e) {
         NetworkPacket packet;
         if (--counter > 0) {
             // {"a":13,"c":1,"p":{"c":"msg","p":{"arr":["GCDS","365587","4"]},"r":365587}}
@@ -165,8 +165,8 @@ class GauntletLevelLoadedHandler : ICommandHandler
                 room.Id.ToString()
             }, "msg", room.Id);
             
-            timer.Stop();
-            timer.Close();
+            timer!.Stop();
+            timer!.Close();
             timer = null;
         }
         foreach (var roomClient in room.Clients) {
@@ -181,7 +181,7 @@ class GauntletRelayGameDataHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) // {"a":13,"c":1,"p":{"c":"gs.RGD","p":{"0":"2700","1":"78","en":"GauntletGameExtension"},"r":4}}
     {
-        GauntletRoom room = client.Room as GauntletRoom;
+        GauntletRoom room = (client.Room as GauntletRoom)!;
         NetworkObject p = receivedObject.Get<NetworkObject>("p");
         
         // {"a":13,"c":1,"p":{"c":"msg","p":{"arr":["RGD","365587","150","75"]},"r":365587}}
@@ -204,7 +204,7 @@ class GauntletGameCompleteHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) // {"a":13,"c":1,"p":{"c":"gs.GC","p":{"0":"1550","1":"84","en":"GauntletGameExtension"},"r":4}}
     {
-        GauntletRoom room = client.Room as GauntletRoom;
+        GauntletRoom room = (client.Room as GauntletRoom)!;
         NetworkObject p = receivedObject.Get<NetworkObject>("p");
         
         room.ProcessResult(client, p.Get<string>("0"), p.Get<string>("1"));
diff --git a/src/CommandHandlers/RacingHandlers.cs b/src/CommandHandlers/RacingHandlers.cs
index 0c31a57..b1a2da4 100644
--- a/src/CommandHandlers/RacingHandlers.cs
+++ b/src/CommandHandlers/RacingHandlers.cs
@@ -18,7 +18,7 @@ class RacingPlayerReadyHandler : ICommandHandler
         // so server do not need generate this packet
         
         if (client.Room.Group == "RacingDragon") {
-            RacingRoom room = client.Room as RacingRoom;
+            RacingRoom room = (client.Room as RacingRoom)!;
             room.SetPlayerState(client, ready);
             Console.WriteLine($"IMR Lobby: {client.ClientID} {ready}");
             room.TryLoad();
@@ -44,7 +44,7 @@ class RacingPlayerStatusHandler : ICommandHandler
 class RacingUACKHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) {
-        RacingRoom room = client.Room as RacingRoom;
+        RacingRoom room = (client.Room as RacingRoom)!;
         room.SetPlayerState(client, RacingPlayerState.RaceReady1);
     }
 }
@@ -54,7 +54,7 @@ class RacingUACKHandler : ICommandHandler
 class RacingARACKHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) {
-        RacingRoom room = client.Room as RacingRoom;
+        RacingRoom room = (client.Room as RacingRoom)!;
         room.SetPlayerState(client, RacingPlayerState.RaceReady2);
 
         if (room.GetPlayersCount(RacingPlayerState.RaceReady2) == room.ClientsCount) {
@@ -71,7 +71,7 @@ class RacingARACKHandler : ICommandHandler
 class RacingARHandler : ICommandHandler
 {
     public void Handle(Client client, NetworkObject receivedObject) { // {"a":13,"c":1,"p":{"c":"dr.AR","p":{"CT":"112.1268","FD":"3008.283","LC":"3","UN":"scourgexxwulf","en":""},"r":412467}}
-        RacingRoom room = client.Room as RacingRoom;
+        RacingRoom room = (client.Room as RacingRoom)!;
         NetworkObject p = receivedObject.Get<NetworkObject>("p");
         
         room.SetResults(client, p.Get<string>("UN"), p.Get<string>("CT"), p.Get<string>("LC"));
diff --git a/src/Core/GauntletRoom.cs b/src/Core/GauntletRoom.cs
index de62ff9..800e989 100644
--- a/src/Core/GauntletRoom.cs
+++ b/src/Core/GauntletRoom.cs
@@ -3,34 +3,38 @@ using sodoffmmo.Data;
 
 namespace sodoffmmo.Core;
 public class GauntletRoom : Room {
-    static GauntletRoom NextRoom = null;
+    static GauntletRoom? NextRoom = null;
 
     public static GauntletRoom Get() {
         if (NextRoom != null && NextRoom.ClientsCount == 1) {
-            var ret = NextRoom;
+            var ret = NextRoom!;
             NextRoom = null;
             return ret;
         } else {
             NextRoom = new GauntletRoom();
-            return NextRoom;
+            return NextRoom!;
         }
     }
 
-    public GauntletRoom(string name = null) : base (name, "GauntletDO", true) {
+    public GauntletRoom() : base (null, "GauntletDO", true) {
         base.RoomVariables.Add(NetworkArray.VlElement("IS_RACE_ROOM", true));
     }
 
     class Status {
         public string uid;
         public bool isReady = false;
-        public string resultA = null;
-        public string resultB = null;
+        public string resultA = "";
+        public string resultB = "";
+
+        public Status(string uid) {
+            this.uid = uid;
+        }
     }
 
     private Dictionary<Client, Status> players = new();
 
     public void AddPlayer(Client client) {
-        players[client] = new Status { uid = client.PlayerData.Uid };
+        players[client] = new Status(client.PlayerData.Uid);
     }
 
     public void SetPlayerReady(Client client, bool status = true) {
@@ -51,7 +55,6 @@ public class GauntletRoom : Room {
         info.Add("UJR"); // User Joined Room
         info.Add(base.Id.ToString());
         info.Add("2");
-        int i = 0;
         foreach(var player in players) {
             info.Add(player.Value.uid);
             info.Add(player.Value.isReady.ToString());
@@ -70,7 +73,6 @@ public class GauntletRoom : Room {
         info.Add("PA"); // Play Again
         info.Add(base.Id.ToString());
         info.Add("1");
-        int i = 0;
         foreach(var player in players) {
             info.Add(player.Value.uid);
             info.Add(player.Value.isReady.ToString());
@@ -88,7 +90,7 @@ public class GauntletRoom : Room {
 
             int count = 0;
             foreach(var player in players) {
-                if (player.Value.resultA != null) ++count;
+                if (player.Value.resultB != "") ++count;
             }
             if (count != 2)
                 return false;
@@ -98,7 +100,7 @@ public class GauntletRoom : Room {
             info.Add("GC");
             info.Add(base.Id.ToString());
             foreach(var player in players) {
-                if (player.Value.resultA is null)
+                if (player.Value.resultB == "")
                     continue;
                 info.Add(player.Value.uid);
                 info.Add(player.Value.resultA);
@@ -117,7 +119,7 @@ public class GauntletRoom : Room {
 
     static object joinLock = new object();
 
-    static public void Join(Client client, GauntletRoom room = null) {
+    static public void Join(Client client, GauntletRoom? room = null) {
         lock(joinLock) {
             if (room is null)
                 room = GauntletRoom.Get();
diff --git a/src/Core/Racing.cs b/src/Core/Racing.cs
index ff370fa..3f76902 100644
--- a/src/Core/Racing.cs
+++ b/src/Core/Racing.cs
@@ -19,12 +19,8 @@ public class RacingRoom : Room {
         return new RacingRoom();
     }
 
-    public RacingRoom(string name = null, int? trackId = null) : base (name, "RacingDragon", true) {
-       if (trackId is null) {
-            TID = random.Next(105);
-        } else {
-            TID = (int)trackId;
-        }
+    public RacingRoom() : base (null, "RacingDragon", true) {
+        TID = random.Next(105);
 
         players = new();
         results = new();
@@ -66,6 +62,12 @@ public class RacingRoom : Room {
         public string userName;
         public string time;
         public string laps;
+
+        public Result(string userName, string time, string laps) {
+            this.userName = userName;
+            this.time = time;
+            this.laps = laps;
+        }
     }
 
     SortedDictionary<float, Result> results;
@@ -75,11 +77,7 @@ public class RacingRoom : Room {
         while (results.ContainsKey(timef))
             timef += 0.000001f;
 
-        results.Add(timef, new Result {
-            userName = userName,
-            time = time,
-            laps = laps
-        });
+        results.Add(timef, new Result(userName, time, laps));
     }
 
     public void SendResults() {
@@ -104,7 +102,7 @@ public class RacingRoom : Room {
 
     // start and countdown
 
-    System.Timers.Timer timer;
+    System.Timers.Timer? timer = null;
     int counter;
 
     private void SetTimer(double timeout, System.Timers.ElapsedEventHandler callback, bool AutoReset = false) {
@@ -124,7 +122,7 @@ public class RacingRoom : Room {
         SetTimer(0.2, SendJoin);
     }
 
-    private void SendJoin(Object source, ElapsedEventArgs e) {
+    private void SendJoin(Object? source, ElapsedEventArgs e) {
         foreach(var player in players) {
             Console.WriteLine($"Join Racing Room: {Name} RoomID: {Id} IID: {player.Key.ClientID}");
             player.Key.JoinRoom(this);
@@ -132,7 +130,7 @@ public class RacingRoom : Room {
         SetTimer(1, CountDown, true);
     }
 
-    private void CountDown(Object source, ElapsedEventArgs e) {
+    private void CountDown(Object? source, ElapsedEventArgs e) {
         if (!TryLoad()) {
             if (counter == 0) {
                 Load();
@@ -160,8 +158,8 @@ public class RacingRoom : Room {
     }
 
     public void Load() {
-        timer.Stop();
-        timer.Close();
+        timer!.Stop();
+        timer!.Close();
 
         // {"a":13,"c":1,"p":{"c":"","p":{"arr":["RA","","ST"]},"r":412467}}
         NetworkPacket packet = Utils.ArrNetworkPacket(new string[] {
@@ -216,6 +214,9 @@ public class RacingLobby {
     class Status {
         public string uid;
         public RacingPlayerState state = RacingPlayerState.NotReady;
+        public Status (string uid) {
+            this.uid = uid;
+        }
     }
 
     static object lobbyLock = new object();
@@ -225,7 +226,7 @@ public class RacingLobby {
     public static void SetPlayerState(Client client, RacingPlayerState state) {
         lock (lobbyLock) {
             if (!lobbyPlayers.ContainsKey(client)) {
-                lobbyPlayers[client] = new Status { uid = client.PlayerData.Uid };
+                lobbyPlayers[client] = new Status(client.PlayerData.Uid);
             }
             lobbyPlayers[client].state = state;
         }
diff --git a/src/Core/Room.cs b/src/Core/Room.cs
index 7fc3c40..c44dd89 100644
--- a/src/Core/Room.cs
+++ b/src/Core/Room.cs
@@ -16,15 +16,15 @@ public class Room {
     public bool IsRemoved { get; private set; } = false;
     public NetworkArray RoomVariables = new();
 
-    public Room(string name, string group = null, bool autoRemove = false) {
+    public Room(string? name, string? group = null, bool autoRemove = false) {
         Id = ++MaxId;
         if (name is null) {
-            Name = group + "_" + MaxId;
+            Name = group! + "_" + MaxId;
         } else {
             Name = name;
         }
         if (group is null) {
-            Group = name;
+            Group = name!;
         } else {
             Group = group;
         }
diff --git a/src/Core/WorldEvent.cs b/src/Core/WorldEvent.cs
index 603ea1a..264f1bb 100644
--- a/src/Core/WorldEvent.cs
+++ b/src/Core/WorldEvent.cs
@@ -9,10 +9,10 @@ class WorldEvent {
         End,
         NotActive
     }
-    private static WorldEvent _instance = null;
+    private static WorldEvent? _instance = null;
     private object EventLock = new object();
     private Random random = new Random();
-    private System.Timers.Timer timer = null;
+    private System.Timers.Timer? timer = null;
     
     public static WorldEvent Get() {
         if (_instance == null) {
@@ -24,6 +24,7 @@ class WorldEvent {
     private WorldEvent() {
         startTime = DateTime.UtcNow.AddMinutes(-60);
         startTimeString = startTime.ToString("MM/dd/yyyy HH:mm:ss");
+        room = Room.GetOrAdd("HubTrainingDO");
         uid = "sodoff";
         state = State.End;
         ScheduleEvent(Configuration.ServerConfiguration.FirstEventTimer); // WE_ != WEN_
@@ -32,7 +33,7 @@ class WorldEvent {
     // controlled (init/reset) by Reset()
     private Room room;
     private string uid;
-    private Client operatorAI;
+    private Client? operatorAI;
     private State state;
     
     private DateTime startTime;
@@ -51,7 +52,6 @@ class WorldEvent {
     // reset event - set new id, start time, end time, etc
     private void Reset(DateTime newStartTime) {
         lock (EventLock) {
-            room = Room.GetOrAdd("HubTrainingDO");
             uid = Path.GetRandomFileName().Substring(0, 8); // this is used as RandomSeed for random select ship variant
             operatorAI = null;
             state = State.NotActive;
@@ -87,7 +87,7 @@ class WorldEvent {
     }
     
     // reset event and set timer to call PreEndEvent, send new WE_ info
-    private void PreInit(Object source, ElapsedEventArgs e) {
+    private void PreInit(Object? source, ElapsedEventArgs e) {
         Reset(nextStartTime); // WE_ == WEN_
         AnnounceEvent();
     }
@@ -114,7 +114,7 @@ class WorldEvent {
         }
     }
     
-    private void PreEndEvent(Object source, ElapsedEventArgs e) {
+    private void PreEndEvent(Object? source, ElapsedEventArgs e) {
         Console.WriteLine($"Event {uid} force end from timer");
         EndEvent(true);
     }
@@ -152,7 +152,7 @@ class WorldEvent {
     }
     
     // send reward info
-    private void PostEndEvent1(Object source, ElapsedEventArgs e) {
+    private void PostEndEvent1(Object? source, ElapsedEventArgs e) {
             NetworkPacket packet = Utils.VlNetworkPacket(
                 "WE_ScoutAttack_End",
                 lastResults,
@@ -179,7 +179,7 @@ class WorldEvent {
     }
     
     // schedule next event, set timer to call PreInit() and send new WEN_ info
-    private void PostEndEvent2(Object source, ElapsedEventArgs e) {
+    private void PostEndEvent2(Object? source, ElapsedEventArgs e) {
         ScheduleEvent(); // WE_ != WEN_
         AnnounceEvent(false, true); // send only WEN_ (WE_ should stay unchanged ... as WE_..._End)
     }
diff --git a/src/Data/NetworkArray.cs b/src/Data/NetworkArray.cs
index abc0b11..89d7252 100644
--- a/src/Data/NetworkArray.cs
+++ b/src/Data/NetworkArray.cs
@@ -103,7 +103,7 @@ public class NetworkArray {
     }
 
     public class NullClass {};
-    public static NullClass NULL;
+    public static NullClass NULL = new ();
     
     public void AddWithType<T>(T value) {
         if (typeof(T) == typeof(NullClass))
@@ -120,7 +120,7 @@ public class NetworkArray {
             throw new Exception("Unsupported type");
     }
     
-    private void AddWithTypeObject(NetworkDataType dataType, byte typeId, object obj) {
+    private void AddWithTypeObject(NetworkDataType dataType, byte typeId, object? obj) {
         Add(new DataWrapper(NetworkDataType.Byte,typeId));
         Add(new DataWrapper(dataType, obj));
     }