I really like what you are making! But i have 3 tips: 1, arthur can't shoot left so when the zombie is on the left of him he can't hit it. 2, You can see the zombie when he's undergound/hiding, you can just tell the game to make that player sprite nothing and then change the sprite back to the zombie when he appears again. 3, perhaps use set kernel_options no_blank_lines. You'll use the missile you need, that's for sure, but you can use the ball sprite and make arthur shoot that. Anyways, i wish you a verry nice day!