You know tetris, right? Same thing, only on a multitouch device, made for multiple cooperating players. Rotating the pieces is done using the standard multitouch gestures. Finally, we can use them for something other than moving photos around.

multitetris was written by Ka-Ping Yee, mostly on Jan. 3, 2010, at the multitouch hackfest in the c-base. It is Open Source and licensed under the GPL. You can get the source code using

git clone

There is an Ubuntu package for multitetris.