If this game is any indication, third place in the Game Jam contest is like being third best local part-time MacDonald's employee - it might be true, but it's certainly nothing to brag about.
Some games (I Want To Be The Guy) make obstacles ambiguous as part of the challenge and charm - the ambiguity of these were neither. First of all, graphically - Is this bubbling brown stuff hot Mud? If it stopped bubbling when it was cold and didn't hurt me any more, that would make more sense with your theme. Same with the ice: Why am I freezing when it's hot enough out to spontaneously cause the ground to burst into flame? I did figure out through trial and error that brown killed me while blue only slowed me down, so... yay?
The layout of certain obstacles was somewhat confusing as well, from a gameplay standpoint. You put fire above bubbling brown stuff, which gives me an interesting choice: If I'm falling toward it, I can either die medium rare or well done. Unless I'm falling toward the fire-above-pit, which opens up the "crushed" option.
There should be some indication of inactive obstacles in the other world. After accidentally switching worlds directly into a fire bath, I had to jump in the air every time I switched or risk restarting the level eighty times. I felt like one of those ADD guys in World of Warcraft who hop around the screen whenever they stop killing something for eight seconds.
Another interesting choice: Usually a forward-moving screen is used to motivate forward progress. Yours only seemed to keep the player from progressing too fast through the level. I would run up to where the screen had scrolled, get up, make a sandwich, and then come back to play some more.
I'm also wondering if the jump mechanics were tweaked deliberately or not. I'm not complaining about this, though; it was fun being able to fall off a platform and jump in mid-air a moment before ambiguous brown bubbly death.
In conclusion, the game is a good starting point, but needed a lot of tweaking before it was anywhere near the quality of most other games on this site. Maybe if you'd had more time to play test it before its' debut?