While the original Marathon is out now on Steam, sequels Marathon 2: Durandal and Marathon Infinity will be added at a later date. It is worth noting that these are modified versions of the original games, with painstaking work taken on by the Aleph One community to ensure that the game runs properly on modern systems.

The Marathon trilogy was a series of classic shooters made exclusively for Macintosh computers of the time. Since then, the three games have gotten a cult following, thanks in large part to how many of the seeds for storylines that take place in Halo were originally planted in the Marathon games.

Plans to release Marathon on Steam were first announced back in March. The Aleph One version of Marathon features several improvements over the original game, including support for 60+ FPS, and even a HUD.

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