Set up C# solution

src/Main.cs

@@ -0,0 +1,25 @@
+namespace GameJamDungeon;
+
+using Godot;
+
+#if DEBUG
+using System.Reflection;
+#endif
+
+// This entry-point file is responsible for determining if we should run tests.
+//
+// If you want to edit your game's main entry-point, please see Game.tscn and
+// Game.cs instead.
+
+public partial class Main : Node2D
+{
+
+  public override void _Ready()
+  {
+    // If we don't need to run tests, we can just switch to the game scene.
+    CallDeferred("RunScene");
+  }
+
+  private void RunScene()
+    => GetTree().ChangeSceneToFile("res://src/app/App.tscn");
+}