Thanks to the help of some friendly open source developers and creators of Aleph One, the entire trilogy of Bungie’s Marathon is now available for free on all PC platforms. The game that pre-dates the Halo series and gave Bungie their first recognizable hit, and while the series’ aren’t related, any Halo fan will want a chance to see the influence that appears throughout.

The game will be released on a game engine built on Marathon 2‘s source code that has been reworked to be optimized for modern-day PC. This means the games will feature things like OpenGL shader support, Internet co-op and multiplayer, modern mouse-look, gamepad support, HD textures and user mods. I don’t know what most of that means, but I’m sure it’s impressive. Download it here.