It's one of the most co-op family friendly series out there, the LEGO games from Travelers' Tales are a staple to any family's gaming regiment. The latest title is back in the Star Wars Universe, specifically modeled after The Clone Wars TV show.
LEGO Star Wars III: The Clone Wars is out on a myriad of platforms - Xbox 360, PlayStation 3, PC, Wii, DS and PSP. The game supports two player co-op through the entire campaign, though only the Xbox 360 and PlayStation 3 support it online. The rest support couch co-op play.
You can snag the version of your choice right now through Amazon and support Co-Optimus in the process.