Hey there! Firstly I gotta say that I'm the type of person who fails miserably in games like these and gets stuck against a wall all the time, so I guess the fact that it only happened to me once here tells you that level design here is quite solid. The part where I got stuck for a bit was that last jump before the end of level 2, like I was just hanging around in the black world trying to understand how to get that far without considering that there's a wall you can collide off in the white world. I guess this is just a little thing about your gimmick (which I think is very good!), cause whenever you're standing on a platform and you switch, there will no longer be a platform there and you will fall to death, so it's kinda discouraged to be jumping between worlds if you're unsure what to do, so it's hard to discover those features. If you were to finish this project, maybe you could have either a way to check what both worlds look like before starting the level, or a way to see into the other world without really going there (like some kinda lense maybe? like a circle of a certain radius around your mouse that shows what's in that place in the other world?).
But that's about it for complaints, visuals are simple but nice, liked the little eye movements on the character, sound design is interesting, the music shifts between the worlds are a whole mood. The movement felt quite responsive. Good job there!
