I thought it was interesting having some gameplay before the main menu, it took me some time to figure out the wall jump but I enjoyed the discovery process for it. I also think it was interesting how gravity would change from room to room, sometimes being a platformer and other times being a top down style game. I'm impressed by how much you were able to get out of the 72 hours for the jam.
If you wanted to improve, I suggest making the change in gravity more apparent. I always have to take a moment with the rooms to see what to do. Some of the rooms felt unfair, like the one where powerups fell directly on the player's head at the start. I think fixing that some and adding a more consistent jump would make this game spectacular. Overall, good job!