Loved the game and your attention to detail. Felt as an ode to a lot of other games, in a good way. Also loved that from the first jump, you knew right way what kind of game it was, a hard one :-).
In the black and white (starting) world, I did not know what I was dying. When it was color, I found out. It were spikes. I did not see them very well. Also, I did not know the heart counter at the top was counting, was a bit unclear. Some very minor things because this is a good, polished game.