I'd like to see a bit more feedback about interacting with the game world. For example the fact that you die after hitting a red square isn't directly clear. Initially I thought the only lose condition would be when two of the collide.
Also I would maybe spend some time adding art assets to the game and building some kind of reason why you're doing the things you do. I found that adding a lot in my own game and I think it would lift yours up a lot as well.