Treyarch unlocks Black Ops zombie maps

Gamers who haven't yet unlocked all of Black Ops' zombie-based multiplayer modes are to get free access to the hidden content this weekend, developer Treyarch has announced.

To mark the President's Day holiday weekend in the US, the Dead Ops Arcade and Five modes will be open to all players until Monday evening.

For the uninitiated, Dead Ops Arcade sees you and up to three other players pursuing the Cosmic Silverback through a number of zombie-filled arenas filled.

In Five, you'll assume the identity of one of four Cold War icons - John F. Kennedy, Robert McNamara, Fidel Castrol and Richard Nixon as they attempt to rid the Pentagon of wave after wave of ravenous brain-munchers.