Aleph One, a community project, has worked on an "open source continuation of Bungie 's Marathon 2 game engine" for several years. Bungie's classic 1990s trilogy—consisting of Marathon, Marathon 2 and Marathon Infinity—is natively supported on the Aleph One platform (on macOS, Windows, and Linux). The first entry (1994) in the series debuted on Mac systems—Bungie stayed loyal to Apple OS ecosystems with successive titles, but started to shift over to PC platforms with its Myth franchise. A clean break occurred after post Microsoft's takeover, although Halo: Combat Evolved (2001) did eventually land on Mac OS X systems. Long-term Marathon fans have spotted an exciting entry on Valve's Steam store—the Aleph One Developers group has listed a "Classic" version of the first game.

PC Gamer reached out to Bungie for comment on the new-ish listing—a spokesperson responded with this statement: "Yup, this is real, and will be free. We're very supportive of the Marathon community and Aleph One's dedication here to bring the original Marathon to PC, Linux, and Mac for everyone to experience, with cross-platform play available in multiplayer. This is a true tribute to the original game!" The Sony-owned studio is working on a reboot of its classic IP, but that reimagining—as a PvP extraction shooter—is not due anytime soon. The entire original trilogy could be released on Steam by that time (possibly 2025/2026).