According to a Kotaku article, Titan was meant to be an MMO set in near-future Earth after fighting off an alien invasion. Players would do mundane jobs during the day and wage clandestine warfare against other factions at night. Multiple classes, such as Jumper, Reaper, Assassin, Ranger, and Juggernaut, were reinvented into Overwatch's earliest heroes, i.e. Tracer, Reaper, Genji/Hanzo, Widowmaker, and Reinhardt, respectively.
In September 2014, CEO Mike Morhaime revealed in an interview with Polygon that Titan had been canceled.