As an old-school Mac gamer who loved Marathon back in the day (Bungie was originally a Mac-only game studio — Marathon was their breakout game before Halo), I really want to be more excited about this.
But Destiny left me cold, and this leads me to believe that this incarnation of Marathon may do the same: “Marathon is designed from the start as a PvP-focused game and won’t have a single-player campaign.”