I really liked how the controls were introduced as you started the level. The level design itself was nice too, it was good to start with simple challenges to help the player understand the controls, and then move on to tougher challenges.

One thing I was confused about was why you had to activate the mode cartridges once you got them. I only experienced one situation where it was beneficial for me not to activate it until later. I think the waiting concept has some potential though.

For your platform controller, google "coyote time", i think it would help your game a bit. Also, checkpoints are nice, it felt a bit rough to redo the whole game when I missed a jump! Good work though!

Now I am fast. Now I can jump high, and now I can push crates. I liked it. :)