This game is probably my favorite out of all the other entries.
Nice pixel art, consistent style, nice colours etc. GFX do their job.
I'd like there to be visible checkpoints, it would be nice to know I'm "safe" when I make it to certain points. The collision detection was maybe just a little too unforgiving, but at least it is consistent. Perhaps you could add teleport pads or something to help solve backtracking.
I didn't realise you could slide for a long time, so I spent a lot of time frustated with the thwomp-like things XD