You can play the original Marathon trilogy for free with high-resolution graphics.
Long before Halo, Bungie created the Marathon trilogy — a series of first-person shooter games for Mac OS released in 1994, 1995, and 1996. Halo fans may have become somewhat acquainted with the series thanks to Marathon 2: Durandal being released on Xbox Live Arcade in 2007, but that still left two games to be played.
Source code for Marathon 2 was released to the public years ago, prior to Microsoft’s acquisition of Bungie. Subsequently all three games were made available for free from Bungie’s website, including Infinity being made open source this past summer. Not content with having the games to play just as they were originally created, a team of modders has spent the better part of a dozen years working on an updated version of the Aleph One engine, and the Marathon trilogy with it.
That open source engine project has hit a big milestone today with the release of version 1.0. Although the games were already available — the project has set out to introduce features like online multiplayer, mouselook, and gamepad support — you can now download the first versions deemed complete enough to be called version 1.0 on PC, Mac OS X, and Linux.
Those downloading the games will be able to enjoy the original Marathon reworked with high-resolution graphics and a modern HUD in addition to “extensive changes to the scenario to create the most authentic Marathon experience since 1994.” Marathon 2 has been updated to include the high-res graphics seen in the XBLA release (pictured above). Infinity, the third game in the trilogy, also now has high-res graphics.
You can download each of the games, complete with all of these additions, from the project’s official website where you can also find a list of system requirements and a changelist. Suffice it to say, with games this old, even a fairly old computer will manage to run them without issue.