This is not my only Global Game Jam entry but it's definitely the most playable. Coding in Lua with fierydrake we created a memory game where you need to draw patterns, type words and play sounds, remembering the entire series you have learned after each new card is added. Play in browser or download.
For the first Procedural Generation Jam I created a non-interactive Unity project that uses recordings of individual drum hits and designs a constantly evolving electronic drum beat. The forty samples are either my own recordings, from royalty-free sample packs, or generated with bfxr.