Fog is just atmospheric as Edit pointed out, I kept it to obfuscate the fact that there isn't much terrain besides what you interact with :P
I'm exploring the idea of making a puzzle-like climbing game. Ripe for speed-running and all. Definitely will build on this mechanic, since it's near and dear to me.
If you want a bit more of a challenge, you can hunt the 4 notes. They are in harder to reach areas :)