All games entered for GGJ are released under a Creative Commons share, alter, no sell license. You can browse through the games and download their source files on the official website, and a couple of publications did quick hands-on playthroughs.
"Although the club is focused on game development, not everyone participating was a computer programmer. Artists and graphic designers were present to help create characters and models for the games. The goal of Global Game Jam is to a stir up a global creative buzz in games while at the same time exploring the process of development."