This is so cool, especially being only 1mb and written in rust. I don't understand much about rust but it seems like you went for pretty low-level crates rather than a more fully fledged game engine like Bevy, is that more for learning?
I would like it if WASD was an option as well, and also the collisions get in the way of movement/jumping a little which took some getting used to. The graphics are charming and the parallax effect is nice. Really nice job, well done :)