Watchmen is prequel, has two playable characters
According to this 1UP preview, the now-announced episodic Watchmen game is a prequel story that contains two playable characters, Rorschach and Nite Owl. From the piece:
Watchmen (the game) dials back the years to when the game's dual playable characters, Rorschach and Nite Owl, are younger, trimmer, more physically fit versions of their older graphic-novel counterparts. In the demo we saw behind closed doors at E3, both Rorschach and Nite Owl were playable, either as a single-player game with an A.I. partner (whichever character you're not playing is controlled by the CPU) or as a co-op splitscreen venture. Since the game takes place before superheroes were outlawed in the graphic novel's timeline, it allows both characters to do what they do best - fight crime.
Lots more through the link.