I really like the design and the variety of the game despite its issues. I got stuck in the very beginning cause I didn't know that blocks don't pull all the way too you and that you had to step further back a bit to get that positive block out of the top platform. I feel like it would be better if blocks could be pulled right up to the player rather than a significant distance from the player. The rolling mechanic part of the game was solid, though I kinda felt that the collision on the second presser was a bit off cause it would sometimes still get me even when it looked like it was all the way up. I also felt that way when I got to the pink stars you had to jump over. if I tried jumping it over while pressing the jump and right key simultaneously, I would would trigger the star when I wasn't even touching it. To jump over them I had to first press jump, wait till I was almost all the way up, and then press right to fly over the star safely. So ya the collision detection should definitely be reexamined. Like I said though I really like your design approach; in this short demo there wasn't a dull moment and there's lots of variety. An idea I had is, what if you could use the positive and negative blocks to influence your jump height? Like, if you jump off of a positive block while your character is in positive mode, it will repel you and you would be able to jump higher which would perhaps allow you to reach a higher platform. And negative blocks could be used in a similar way. So ya there is lots of ways you can build on this game's concept. I ended up playing through and beating the whole game despite the collision issues I came across, so good work!