A very good platformer! I always like the idea of single player co-op. One thing I’d add is the ability to jump down from a platform, so the player can go back in case they are stuck. I’ve gotten to a point when I’m standing in front of a closed door and I can’t open it in any way. I tried jumping around to see if there’s another way I didn’t notice at first, but it looks like I’m simply done. Other than that, a really nice entry. Well done!