Cool stuff, no pun intended ;P Since I'm on Linux and had to download the project anyway, I did some tinkering. I found adding diagonal movement made it much easier (HAX :D). This broke the anim initially, but after I changed the y anim code to 'elif' instead of 'if' it worked fine :)
I did get confused on how the temperature thing worked, which seems only to affect enemies. Maybe they could change color instead of the player, since there doesn't seem to any effect on them.
Anyhow, good work; very useful to dig into other peoples projects :)