This is a great little game, lots of cool mechanics and fun levels!
A few minor niggles: as others have said, some of the levels (especially the later ones) are prone to cheese, and the spike hitboxes are quite unforgiving.
I also noticed a bug: after beating world 4 (but before unlocking all the emblems), the level select screen prompted me to play 5-1. When I pressed confirm, the game crashed.
