Neat concept
I like the idea.
-Pros: It's somewhat challenging to get started, but easy to master quickly. This has smooth animation. Fairly creative character design gives the game a carefree feel.
-Cons: It's sort of easy to cheat. You can just jump and let go of the balloon to have it float up a little and grab onto it after you fall down again as it keeps getting higher. Your 'back' button at the end of the animation doesn't work either.
-Suggestions: There were no instructions as to what to do. Please tell us what we're getting ourselves into! A keymap for controls would have been nice too, especially since this is a two player game. Also, it seemed like different colored balloons rose higher much faster than the rest. If that's true, please provide a color map if you can (with corresponding balloon speed).
*This is a fun little game for a player vs. player challenge, just fix a few things here and there.