Old Bungie games Marathon, Marathon 2: Durandal and Marathon Infinity have been remastered and released, for free, on PC, Mac and Linux.
The Marathon trilogy has been available as freeware online for six years. The important point here is the "remastered" part.
Open source project Aleph One has enhanced Bungie's Marathon games with OpenGL shader support, online co-op and multiplayer, mouse-look, game pad support and plug-in support for mods.
And after 12 years, Aleph One has just reached version 1.0, which enables multiple platform support and brings new graphical capabilities.
Specifically, Marathon now has a modern HUD, high resolution graphics and "extensive changes to the scenario".
Marathon 2: Durandal has the high resolution graphics seen in the Xbox Live Arcade version of the game. And Marathon Infinity also now sports high resolution looks.
Marathon, released originally in 1994, was Halo creator Bungie's second ever game. It's was/is a futuristic first-person shooter set on colony spaceship called Marathon, which aliens invade. Marathon was billed as the Mac's answer to Doom on PC.
Marathon 2: Durandal appeared a year later on PC then Mac. The game was tarted up for Xbox Live Arcade in 2007. Eurogamer's Marathon 2: Durandal XBLA review awarded 6/10.
Marathon Infinity, released in 1996, reverted back to Mac and ended the trilogy. The eye-catching Infinity addition was Forge, Bungie's level-creating software that fans of Halo will be familiar with.