diff --git a/Shared/World.cs b/Shared/World.cs
index a0e4870..4af9082 100644
--- a/Shared/World.cs
+++ b/Shared/World.cs
@@ -84,7 +84,7 @@ namespace SemiColinGames {
     public const int TileSize = 16;
     readonly int width;
     readonly int height;
-    readonly Tile[,] tiles;
+    readonly List<Tile> tiles = new List<Tile>();
 
     public int Width { get; }
     public int Height { get; }
@@ -112,7 +112,6 @@ namespace SemiColinGames {
       width = worldDesc.AsQueryable().Max(a => a.Length);
       height = worldDesc.Length;
       Debug.WriteLine("world size: {0}x{1}", width, height);
-      tiles = new Tile[width, height];
       for (int j = 0; j < height; j++) {
         for (int i = 0; i < width; i++) {
           Terrain terrain = Terrain.Empty;
@@ -148,29 +147,24 @@ namespace SemiColinGames {
                 break;
             }
           }
-          var position = new Rectangle(i * TileSize, j * TileSize, TileSize, TileSize);
-          tiles[i, j] = new Tile(texture, terrain, position);
+          if (terrain != Terrain.Empty) {
+            var position = new Rectangle(i * TileSize, j * TileSize, TileSize, TileSize);
+            tiles.Add(new Tile(texture, terrain, position));
+          }
         }
       }
     }
 
     public void Draw(SpriteBatch spriteBatch, Camera camera) {
-      for (int j = 0; j < height; j++) {
-        for (int i = 0; i < width; i++) {
-          tiles[i, j].Draw(spriteBatch, camera);
-        }
+      foreach (Tile t in tiles) {
+        t.Draw(spriteBatch, camera);
       }
     }
 
     public List<Rectangle> CollisionTargets() {
       var result = new List<Rectangle>();
-      for (int j = 0; j < height; j++) {
-        for (int i = 0; i < width; i++) {
-          var t = tiles[i, j];
-          if (t.Terrain != Terrain.Empty) {
-            result.Add(t.Position);
-          }
-        }
+      foreach (Tile t in tiles) {
+        result.Add(t.Position);
       }
       return result;
     }