Co-op Options in Call of Duty: Black Ops (Xbox 360)

No campaign co-op exists. The game does not support split-screen or online co-op for the single-player story.

Multiplayer Modes for 2+ Players

• Local Split-Screen Multiplayer: Up to 2 players on one console (offline or Xbox Live). Modes: Team Deathmatch, Free-for-All, Gun Game, etc.
• Online Multiplayer: Party up with friends (up to 6 in a party) for public matches.
• Zombies (Co-op): 1–4 players online or 2-player split-screen. Maps: Kino der Toten, Five, Dead Ops Arcade, etc.
• Combat Training: Offline bots with up to 2 local players + AI.

For story co-op, look at Black Ops II (campaign co-op added) or Modern Warfare 2/3 Spec Ops mode.