Trollhammer is another Ludum Dare entry and another endless runner. That style of game play makes for a great game jam entry because the level design is so easy to implement. You can rely on a lot of randomness rather than an intricate and precise level design — which takes time!
Trollhammer has a pretty gruesome premise — you are a troll and you must smash all the squishy humans with your hammer — and some incredibly frenetic music. This is possibly my most ambitious artwork for any LD too.