Treyarch's Josh Olin has said that multiplayer in Call of Duty: Black Ops was underway so early that the single-player guys have been using multiplayer assets to speed up production.
"We've had a dedicated team working on that since day one," Olin, who is Treyarch's community manager, told IGN about the online side of the game.
"Let me put it in perspective for you. We had multiplayer started and up and running in the project so early that some single-player levels actually are being built around multiplayer maps that we had in production.
"So it's not the other way around," he said, referring to the accepted wisdom that multiplayer tends to follow single-player. "It's not single-player maps being brought into multiplayer, it's multiplayer being brought into single-player, so that's how ahead of the game they were."
Call of Duty: Black Ops puts players in a team of deniable operatives doing Special Forces business during the Cold War. It takes place in Vietnam and other areas around the globe.
Check out our detailed Call of Duty: Black Ops preview to find out more about the setting, walk through a couple of scenarios and hear about cool weapons like the dragon's-breath explosive shotgun and the crossbow.
Call of Duty: Black Ops is due out for PC, PS3 and Xbox 360 on 9th November.