The Marathon trilogy for iOS can now be yours for free through the App Store. The last game in the set, Marathon Infinity was released yesterday on the service. Each title is free in standard definition, but if you want the games in a higher resolution, each will run you $1.99. There’s also a Master Chief mode for 99¢ which contains cheat options and a level select, and for another 99¢ you can get IAP for various different crosshairs. To reiterate, the games available are: Marathon, Marathon 2: Durandal, and Marathon Infinity. Thanks, Touch Arcade.