diff --git a/blockstile.ts b/blockstile.ts
index fb041ae..02b81d8 100644
--- a/blockstile.ts
+++ b/blockstile.ts
@@ -37,10 +37,10 @@ namespace TileWorld {
      * @param index
      * @param img
      */
-    //% blockId=TWsetsprite block="set sprite %index=colorindexpicker to %img=tile_image_picker"
+    //% blockId=TWsetsprite block="set sprite %index=colorindexpicker to %img=tile_image_picker with $kind=spritekind"
     //% group="Tiles"
-    export function addTileSprite(code: number, image: Image) { 
-        myWorld.addTileSprites(code, image)
+    export function addTileSprite(code: number, image: Image, kind: number) { 
+        myWorld.addTileSprites(code, image, kind)
     }
      /**
      * Set the player
@@ -53,18 +53,8 @@ namespace TileWorld {
         bindToController(player)
         scene.cameraFollowSprite(player)
     }
-    /**
-     * Make a set of values and return the value representing the set
-     */
-    //% group="Tiles"
-    //% blockId=TWmakeset block="make set from %code %code2|| %code3 %code4"
-    //% inlineInputMode=inline
-    export function makeSet(code: number, code2: number, code3: number = 0xff, code4: number = 0xff) {
-        return myWorld.makeGroup(code, code2, code3, code4)
-    }
 
     // notifications
-    //% group="Events"
 
     /**
      * Act on a sprite that is resting on a tile
diff --git a/main.ts b/main.ts
index ec28d21..c4da386 100644
--- a/main.ts
+++ b/main.ts
@@ -190,23 +190,22 @@ let world = new tw.TileWorld()
 world.setMap(levels.level1)
 world.setBackgroundTile(codes.Space)
 
+// names for sets
+
+namespace SpriteKind {
+    export let Rock = SpriteKind.create()
+}
+
 world.addTiles(codes.StrongWall, art.Wall)
 world.addTiles(codes.Wall, art.Wall)
 world.addTiles(codes.Space, art.Space)
 world.addTiles(codes.Dirt, art.Dirt)
 
-world.addTileSprites(codes.Boulder, art.Boulder)
-world.addTileSprites(codes.Diamond, art.Diamond)
-world.addTileSprites(codes.Enemy, art.Enemy)
+world.addTileSprites(codes.Boulder, art.Boulder, SpriteKind.Rock)
+world.addTileSprites(codes.Diamond, art.Diamond, SpriteKind.Rock)
+world.addTileSprites(codes.Enemy, art.Enemy, SpriteKind.Enemy)
 world.addTileSprites(codes.Player, art.Player, SpriteKind.Player)
 
-// names for sets
-
-namespace SpriteKind {
-    export let Wall = world.makeGroup(codes.Wall, codes.StrongWall)
-    export let Rock = world.makeGroup(codes.Boulder, codes.Diamond)
-}
-
 scene.cameraFollowSprite(world.getSprite(codes.Player))
 
 tw.bindToController(world.getSprite(codes.Player))
@@ -244,7 +243,8 @@ world.onTileArrived(SpriteKind.Player, (tile) => {
 world.onTileArrived(SpriteKind.Player, (tile, dir) => {
     world.isNotOneOf(dir, TileDir.None)
     tile.hasNo(codes.Boulder, dir)
-    tile.hasNo(SpriteKind.Wall, dir)
+    tile.hasNo(codes.Wall, dir)
+    tile.hasNo(codes.StrongWall, dir)
     tile.moveOne(dir)  
 })
 
@@ -272,17 +272,17 @@ world.onTileStationary(SpriteKind.Rock, (tile) => {
 
 // rock falls to right
 world.onTileStationary(SpriteKind.Rock, (tile) => {
-    tile.has(SpriteKind.Rock, TileDir.Down)
     tile.has(codes.Space, TileDir.Right)
     tile.has(codes.Space, TileDir.Right, TileDir.Down)
+    tile.has(SpriteKind.Rock, TileDir.Down)
     tile.moveOne(TileDir.Right)
 })
 
 // rock falls to left
 world.onTileStationary(SpriteKind.Rock, (tile) => {
-    tile.has(SpriteKind.Rock, TileDir.Down)
     tile.has(codes.Space, TileDir.Left)
     tile.has(codes.Space, TileDir.Left, TileDir.Down)
+    tile.has(SpriteKind.Rock, TileDir.Down)
     tile.moveOne(TileDir.Left)
 })
 
diff --git a/tileworld.ts b/tileworld.ts
index e6e6a96..f939364 100644
--- a/tileworld.ts
+++ b/tileworld.ts
@@ -50,7 +50,8 @@ namespace TileWorld {
         } 
         // conditions
 
-        // block
+        //% blockId=TWhas block="%this(sprite) has %code=colorindexpicker at %dir || %dir2 %dir3"
+        //% group="Conditions" color="#448844" inlineInputMode=inline
         has(code: number, dir: TileDir = TileDir.None, dir2: TileDir = TileDir.None, dir3: TileDir = TileDir.None) {
             this.parent.check(this.parent.containsAt(code, this, dir, dir2, dir3))
         }
@@ -322,6 +323,7 @@ namespace TileWorld {
             scene.setTile(code, art);
             this.sprites[code] = []
             this.spriteCodes.push(code);
+            this.codeToKind[code] = kind;
             for (let value of tiles) {
                 let tileSprite = new TileSprite(this, code, art, kind)
                 this.sprites[code].push(tileSprite)
@@ -342,22 +344,6 @@ namespace TileWorld {
             }
         }
 
-        makeGroup(code: number, code2: number, code3: number = 0xff, code4: number = 0xff) {
-            let kind = SpriteKind.create()
-            this.codeToKind[code] = kind;
-            this.codeToKind[code2] = kind;
-            this.setKind(code, kind); this.setKind(code2, kind)
-            if (code3 != 0xff) {
-                this.codeToKind[code3] = kind;
-                this.setKind(code3, kind);
-            }
-            if (code4 != 0xff) {
-                this.codeToKind[code4] = kind;
-                this.setKind(code4, kind);
-            }
-            return kind;
-        }
-
         onTileStationary(kind: number, h: (ts: TileSprite) => void) {
             if (!this.stationaryHandlers[kind]) {
                 this.stationaryHandlers[kind] = []