One week ago Bungie filed a new trademark application for Marathon, the FPS superstar of Mac gaming's brief apogee during the mid- to late-1990s. There are few details beyond that but the paperwork's enough to stoke fantasies of a reboot.
It's definitely Bungie filing it, though the application notes the first use in commerce was Jan. 1, 1995, so this could just be some housekeeping required to keep that mark fresh for the studio. Marathon, in addition to having bitchin' box art also during that period's heydey, released for the Mac in late Dec. 1994, and spawned a sequel in November 1995.
Also keep in mind that Bungie seemed to have something Marathon related at X10.
Xbox Live released a port of Marathon 2: Durandal in 2007, which is still available in Marketplace. That version is noted for its high framerate apparently eliciting so many motion sickness complaints that it comes with cautionary messages and had to be patched to allow players to change their field of view.
Marathon [US Patent and Trademark Office via Superannuation]