via O'Reilly Mac OS X Conference | Frankentosh: Creating Robots on Mac - IBM's Robocode

"Build the best. Destroy the rest. In Robocode, you'll program a robotic battletank in Java for a fight to the finish. The game is designed to help you learn Java, and have fun doing it... from a simple 10-line robot to a very sophisticated, intelligent robot that destroys the competition!"

Not sure this is exactly PC but I'm quite certain it'll appeal to some of our students. More details in the developerWorks: Java technology : Rock 'em, sock 'em Robocode! article:

"Is it possible to learn inheritance, polymorphism, event handling, and inner classes, all while dodging bullets and executing precision attack maneuvers? A surprisingly addictive teaching-tool-turned-game-craze called Robocode is about to make this a reality for Java developers worldwide. Follow along as Sing Li disarms Robocode and starts you on your way to building your own customized lean, mean, fighting machine."