Bungie's Marathon was a groundbreaking and utterly brilliant FPS released for the Mac, back in 1994 when Halo couldn't have been more than a sketchy fantasy. As a testament to its quality and visual bauty, the original Marathon went on to spawn two sequels and then got itself ported to a variety of systems, including, yes, the excellent Dreamcast. What's more, Marathon 1 can now be grabbed for free for your iPad via the App Store. It's a pretty excellent port that sports some equally lovely in-app purchases mind; namely an HD and a Master Chief mode. Enjoy!