COSI, on 2015-04-11, got together to write roguelike's in seven hours. It actually ended up being more like 5 hours, due to a fire alarm going off - sources say it was a chemical fire.
This is ralphie, my take on it. The code isn't the greatest, but it plays - other than not having too much to do, it's actually pretty fun.
Some others from the same event: