Added Tile collision detection

GameBoard.cs

@@ -0,0 +1,79 @@
+using Godot;
+
+public partial class GameBoard : Node2D
+{
+    private PuzzleTile[,] _grid = new PuzzleTile[5, 4];
+
+    private PuzzleTile _activeTile;
+
+    // FIX 1: Use GD.Load and explicitly cast it to (PackedScene)
+    private PackedScene _tileScene = (PackedScene)GD.Load("res://PuzzleTile.tscn");
+
+    public override void _Ready()
+    {
+        // FIX 2: Explicitly cast the returned Node to (PuzzleTile)
+        _activeTile = (PuzzleTile)GetNode("PuzzleTile");
+        _activeTile.GridX = 0;
+        _activeTile.GridY = 0;
+
+        _grid[0, 0] = _activeTile;
+
+        SpawnObstacle(4, 0);
+    }
+
+    private void SpawnObstacle(int x, int y)
+    {
+        // FIX 3: Explicitly cast the instantiated object to (PuzzleTile)
+        PuzzleTile obstacle = (PuzzleTile)_tileScene.Instantiate();
+        AddChild(obstacle);
+
+        obstacle.GridX = x;
+        obstacle.GridY = y;
+        obstacle.Position = new Vector2(x * 128, y * 128);
+        obstacle.Modulate = new Color(1, 0, 0);
+
+        _grid[x, y] = obstacle;
+    }
+
+    public override void _Process(double delta)
+    {
+        if (_activeTile == null || _activeTile.IsMoving) return;
+
+        Vector2 direction = Vector2.Zero;
+        if (Input.IsActionJustPressed("ui_right")) direction.X = 1;
+        else if (Input.IsActionJustPressed("ui_left")) direction.X = -1;
+        else if (Input.IsActionJustPressed("ui_down")) direction.Y = 1;
+        else if (Input.IsActionJustPressed("ui_up")) direction.Y = -1;
+
+        if (direction != Vector2.Zero)
+        {
+            CalculateSlide(_activeTile, (int)direction.X, (int)direction.Y);
+        }
+    }
+
+    private void CalculateSlide(PuzzleTile tile, int dirX, int dirY)
+    {
+        int testX = tile.GridX;
+        int testY = tile.GridY;
+
+        while (true)
+        {
+            int nextX = testX + dirX;
+            int nextY = testY + dirY;
+
+            if (nextX < 0 || nextX >= 5 || nextY < 0 || nextY >= 4) break;
+
+            if (_grid[nextX, nextY] != null) break;
+
+            testX = nextX;
+            testY = nextY;
+        }
+
+        if (testX == tile.GridX && testY == tile.GridY) return;
+
+        _grid[tile.GridX, tile.GridY] = null;
+        _grid[testX, testY] = tile;
+
+        tile.SlideTo(testX, testY);
+    }
+}