Really love the retro graphics and style of gameplay. I think you should add a "try again" or "replay" button at the end of the game. Also, have you changed the magic spell keys in the WASD version? I don't think ZXC can work with WASD for movement, unless you allow mouseclick for movement, but then you'd have to change default shooting. Also, what are you planning on including in the 'menu'? Maybe have some coin/money system where you can buy upgrades.