I want to host some LAN parties this winter, and am looking for some Free Software Games that would be a fun time. We already play some Counterstrike and StarCraft 2, but I want to expand into some actual Free games. Windows compatibility is a must, MacOS compatibility is desirable!

The two on my radar are:

• Hedgewars, which seems like a strong candidate. We played a ton of Worms 2 in the 90s
• 0 A.D., since we're already fans of RTS games.

But I know there must be some wacky ones out there which would be suitable for 30 minutes of pick up play.