I tried out the first few stages and I really like how the jumping feels (the particles and it feels snappy). But I'm not sure, are the doors supposed to be checkpoints, because if I die I've to start at the beginning again.
Anyways I'll probably try to finish it later today, after work. It feels fun so far.
Edit: I get it now, I need the gems to activate the doors. Should've read more carfully.
Edit 2: So I finished the game, sadly I could not get the last gem. The music is good and does not get boring. The levels are fun and challenging, but they are quite difficult though (which is not bad). The hidden gems were a nice touch. Sadly I can't go back and try to get the last gem after reaching the endscreen. It is a nice entry, even if the tileset may felt unfinished.