diff --git a/Engine.Core/Engine.Core.csproj b/Engine.Core/Engine.Core.csproj
index eaf7af4..ad9c883 100644
--- a/Engine.Core/Engine.Core.csproj
+++ b/Engine.Core/Engine.Core.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
+    <ImplicitUsings>false</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
diff --git a/Engine.Core/GameManager.cs b/Engine.Core/GameManager.cs
index eb26a8d..c6efd69 100644
--- a/Engine.Core/GameManager.cs
+++ b/Engine.Core/GameManager.cs
@@ -1,3 +1,6 @@
+using System;
+using System.Collections.Generic;
+
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;