Players of online fantasy games like World of Warcraft love to anonymously inhabit shamans, mages and other characters. But theyd rather not reveal their real identities, as evidenced by an uproar this week over a plan by Blizzard Entertainment, the creator of World of Warcraft.

On Tuesday, Blizzard announced that it will begin forcing participants in its game discussion forums--where players go to gab about World of Warcraft and other games--to post comments using their real first and last names. The change will go into effect...