Here's a great open-source worms-like game. Which is some what surprising, given that a lot of open source stuff tends to be half-baked and abandoned. But this is pretty good.http://www.hedgewars.org/
and by half-baked and abandoned I mean it's usually somebody's pet project that they do in their spare time by themselves thats not organized very well for the most part, and on an unrelated note, if anybody knows of a semi-decent navigation/trip planning program (think MS streets & trips) that runs under linux I would be very happy to know, because mostly whats out there is half-baked and abandoned. But try hedgewars, I think it's pretty darn good.