The animation needs speeding up, and they don't actually hurt you yet, but these were the last obstacles I had to implement. You'll encounter pools of lava in the final level as well - including the one you'll hurl yourself into to win the game. And the protagonist is now an actual human instead of an orange square, so that's good too.

I've decided against music and instead added a sort of minimalist hum. I think it works better, creates a more ominous tone. The only bits missing now, apart from the geyser collisions, are the final 1 1/2 levels and the win/lose cutscenes. Nearly there!