BioWare's latest release Dragon Age: Origins and next release Mass Effect 2 are single-player games. Ray Muzyka, the studio's co-founder says that they could add co-op to future installments, though.

"Sure. We would consider it. We haven't announced anything on that front yet, but those are interesting ideas," Muzyka said when asked by Videogamer if they'd consider co-op features for ME or DA. "They could make a great gameplay experience. Whether we'll do them or not remains to be decided."

Added Muzyka: "It's hard to weave a great single-player storyline into a multiplayer experience. It's not impossible. We've done it, and we're doing it again now in Star Wars: The Old Republic. But it is challenging."

It's true, they have done it before. The campaigns for Baldur's Gate and Neverwinter Nights could both be played online.