This seems to be a good base for a minimalist platformer. I had some issues with level 3 because the camera is completely snapped to the players x and y coordinates and the level is about precision landing. But between not being able to see where you're going to land and the background being uniform gray, it's nearly impossible to know where to land. It took me 15+ tries to get through that part. I can't remember what level, but the one where you push boxes over the spikes to jump across them safely was hard to get the box to land in a way that would be flat. I couldn't make it past level 7. At first I thought there was an impossible jump. Then I realized the platform moved horizontally, so you just had to wait for it. Waiting in a fast paced platforming game generally kills the fun really really quickly, so I'd try to minimize that. There was also no way of knowing the platform you had to jump to moved since it was off screen. It'd help if there was an indication of there being a moving platform there. Or maybe just having it close and only move when you first jump on it? The vertically moving platform is, I'm pretty sure, impossible to jump on. It's just guesswork to determine when it'll hit the top of the screen going downwards and I couldn't ever land on it no matter how many times I tried. Some sound effects for jumping and dying would go a long way, even just little blips. Music would help a lot, too, but not strictly necessary.