It took me a while, but I finally managed to reach the end. There's a steep learning curve for the controls, but they're really well designed. The wall dash ended up saving me in some parts where it would've taken longer the normal route. There's a lot of potential in this game, especially for speedrunning.
There was a small bug at the end with the last key. I went back a room and then forward again to the snow area, and the key respawned even though I was still holding it. Of course, it didn't matter in the end though.