- Keep Circulating The Tarballs: The Aleph One project, ensuring that Marathon would go on with or without Bungie's guidance (currently with, since Microsoft spun Bungie off again).
- More Than Infinite: The Aleph One engine, named after smallest uncountable infinity.
- Promoted Fanboy: Many, such as Craig Mullins, Randal "Frigidman" Shaw, and Tuncer Deniz.
- Though the “boy” part is a bit misleading in the case of Craig Mullins, as the work that brought him to Bungie's attention shows. The page image on the main page is his work, by the way.
- Sequel First: Marathon 2: Durandal was the only game in series to be officially released outside the Mac for Windows until Bungie made the Trilogy and the Engine freeware and the fans made Aleph One.
- Universe Concordance: Marathon Story Page. It is notable enough to have a official secret map in honor of its Admin.
- What Could Have Been: The original plan for the first game called for the plot to branch at various points depending on how many BoBs you saved in certain levels. This was scrapped and the only remnant of that plan is differing messages from Leela depending on how many of them you saved.
- It is worth noting that the capacity to do this was still built into the engine, and that when a player transitions from the end of one level they can (in theory) be sent to any other map-maker defined level in the game, regardless of level order. While conventionally the player is sent to the next level in the order, some mod-makers have taken full advantage of this ability to alter the next level that the player goes to based on what they accomplished in that level, with resulting branching plotlines.
- The alpha version, which could be described as Pathways into Darkness: Space Edition, was set not on a ship, but a hollowed-out asteroid near Pluto; the Security Officer (if that's even what he was at this stage) is sent to investigate the disappearance of this asteroid's colonists and finds only feral aliens.