In the first level, you have to take advantage of being big or small, and maneuver through thin tunnels. The part with cannons is particularly difficult; you have to tap the jump button very briefly.
The second level is pretty short, and is more of a puzzle. The first half of the level is just fun bouncing and flying, which you get to do several times, as you're expected to die while figuring out the second half.
In the third level, you have to double-jump using Iceblocks. I thought about triple-jumping using two Iceblocks at once, but I haven't been able to do that (if it's possible at all), so I haven't incorporated it into the level.
I also have ideas for a fourth and a fifth level. Be patient.
(Can someone confirm that I've uploaded these correctly?)