WoW took 100+ guys 5 years to finish.
Actually, the core of the game took less than a year to make. All the content and debugging related to it took time. It's that conflict when an artist wants something unavailable, but the feature somehow breaks the nice working code. And of course, the publisher wants the combination invented sometime...
yesterday.
I think that game's starting core only required one to three people, and I'm sure one of them didn't work directly for Blizzard. Otherwise, all else seems true.