Agree with everybody before, but here a few points from bit more actual game-design view (learned from my own game, but also by testing others) :
- Don't make too slow-paced games on a game jam. People have little time, especially in a huge jam like this
- Also test your "dead-ends", and ensure they have no groundbreaking bugs
- Keep your scope small (not especially learned this time, but the scope was again too big^^)
- Focus on one main game-mechanic and polish that one (there are a few very good ones in this jam)
- Use sound, just a little bit can bring your game to a total different level
- If you have a story in your game, ensure asap that at least the keypoints can be reached and the game-loop is complete.
- There are lots of different people playing your game, so ensure difficulty is not too hard.