We've had an idea for our 7DFPS game for a bit now and have been keen to take a week long break from developing our larger game to make something small and fun. We weren't going to bother with the 7 hour jam until we had an idea that didn't sound terrible and could be done to some decent extent in 7 hours.
Here's Hemisphere: http://7dfps.com/?action=games&id=21
It's a first person bullet hell boss fight. Developed further it would have power-ups, ramping difficulty, levels, etc. This 7 hour version is pretty bare bones with some of the core ideas of the radial movement, jump pads, changing weak points, different firing patterns, etc. It's brutally difficult and can be frustrating, but I'm happy with it as a 7 hour prototype.
In a couple of weeks we'll probably look back at it and see if we want to develop it any further.