Up to four players will be able to team together and cleanse the world of foreigners in Call of Duty: Black Ops. In a recent multiplayer reveal at USA Today, it has been confirmed that between two and four players can take part in a co-op mode. Cool.

During the preview, USA Today played a level set in 1968 and discovered a new feature -- alternate ammo which can be changed at will. A provided example was the crossbow, which can switch between regular and explosive arrows.

That's about all that's fresh so far. Expect Treyarch and Activision to show off much more at E3.

First impressions: 'Call of Duty: Black Ops' [USA Today]