Hey, thanks for adding a Mac download. As I have no friends so I checked this out solo, Definately some potential here for a decent sofa local party game. Here are some suggestions if you decide to keep developing it.
Improve the player controls. A jump attack would be the first thing, then maybe a projectile that you have to pick up (spawn it in randomly). I get that it's probablt supposed to be a fast paced game with 1-hit wins but if you add maybe a couple of hit points to prolong each round that would be good. These could be represented by each monkey holding 3 bananas, when you get hit you drop one (which could also then turn into a trap causing any monkey that steps on it to slip and lose 1 banana. (just thinking out loud). Make the sprites smaller and give the player more room to run around and away from the other player/gain vantage positions etc. You may need to increase the level time slightly for this. I think a good 30 seconds per level is probably fine. Also if players are competing, add a score system (for bragging rights).
If I'm missing the scope of what you're were intending to develop then disgregard this, these are just a couple of ideas that I thought of when playing.
Nice game! :)