Even if the controls felt a little slippery, I think that actually did a really nice job of conveying the feeling of being a person navigating a cave they've never seen before, and having to think carefully before each jump. I also love the little sizzle sound effect of landing on the red blocks- it's a nice little touch that elegantly conveys to the player that these aren't just generic instant-death blocks, they're specifically red-hot. Nice work!

Neat way to get the most value out of your content! Lava field were difficult for me. Maybe you could reduce the death range of the lava blocks just slightly to help the player out, so landing off the platform by one pixel doesn't instakill.

Cool concept!  I really like this take on the single-room requirement.