Add initial game code

scripts/MainMenu/MainMenuController.cs

@@ -0,0 +1,28 @@
+using Godot;
+
+public partial class MainMenuController : Node
+{
+	public Button StartGameButton { get; private set; }
+	public Button ExitGameButton { get; private set; }
+
+	public override void _Ready()
+	{
+		base._Ready();
+
+		this.StartGameButton = GetNode<Button>("CenterContainer/VBoxContainer/StartGameButton");
+		this.ExitGameButton = GetNode<Button>("CenterContainer/VBoxContainer/ExitGameButton");
+
+		this.StartGameButton.Pressed += OnStartGame;
+		this.ExitGameButton.Pressed += OnExitGame;
+	}
+
+	public void OnStartGame()
+	{
+		GetTree().ChangeSceneToFile("res://scenes/game.tscn");
+	}
+
+	public void OnExitGame()
+	{
+		GetTree().Quit();
+	}
+}