Hey Renato, thanks a lot for the comment. I hadn't played a game exactly like this before myself, but not too surprised to hear that the idea has been made already. The boxes are mainly the result of me not planning my time well enough :P
Sorry to hear that the game is not playable for you. I did not run into any issue like that during development/play testing. Does it happen constantly, like as soon as you hit restart? It's not that you die due to the top box running into a spike?