Software

While the official Steam version of Call of Duty: Black Ops 1

Yes.

Playing Call of Duty: Black Ops 1 multiplayer offline on PC for free is not only possible but surprisingly easy. The bot AI (even on Veteran) holds up incredibly well. You can level up, grind camos, and learn every map without spending a cent on a 14-year-old game.

Playing Offline

Open the launcher, log in, and point the "T5" (Black Ops 1) tab to your game installation folder. :

Method C: Custom Client Emulators (The Community Solution)

Why Plutonium?