I think the game was really polished and felt like something new! Here are my critiques:
I think there should be some vertical speed cap when falling down because the constant gravity makes it hard to predict where you'll end up.
I also died once by holding right when entering a room because I was moving while the screen started to unveil and couldn't see myself, so I think you shouldn't be able to move until half a second or so after the transition effect.
I feel like the mechanics are introduced too quickly. Maybe there should have been an extra level at the start without spikes and just a room with a bunch of twists and turns to get through.
Also, this is just a nitpick, but I think the background could have had more detail.
Lastly, I think the game was too easy and could have gone on for longer.