Interesting concept, I really like the idea of making different sets and then mixing them in the playlist, kinda feels like working on FL Studio hahaha I love how the UI looks, it's so pleasing to the eyes. It would be nice if you could see the whole level from the start, that way you could try to get it right on the first try, instead of doing trial and error until you get it right.
The only thing that got in the way of me playing for hours was a bug where the character would jump and it wouldn't come back down so each time it jumps it's higher and higher until you can no longer see the level lol.