A funny thing happens with the second checkpoint. You just respawn at the very bottom, with no lava, until you climb and find it above you!
Anyway, the game is really nice! The mechanics are interesting, and it makes a pretty great platformer. The main issue for me is that it was unclear that I had to bounce on at least one wall to be able to "jump" again. Thus I didn't understand at my first attempts why sometimes I was able to jump in mid-air, and sometimes not. But once I got the idea, it was really pleasant. Congrats!