For the full experience, including Zombies and online leaderboards, you would need to buy the game. But for a casual, offline bot-shooter on a budget, Combat Training is a perfectly playable, legal, and free way to relive the golden era of Black Ops .
By default, you start at level 1. To unlock all weapons/perks instantly offline:
You can add bots to your matches by downloading the mod for BO1 from ModDB and placing it in a created mods folder within your game directory. Method 2: "Bot Warfare" Mod (Steam/Retail Version)
Some mods improve bot AI or add bots to custom games where they’re normally missing.
While the official Steam version of Call of Duty: Black Ops 1
: You may need to create a free account on the Plutonium forum for the initial setup, though the client can be forced into "LAN" or "Offline" modes later. 2. Configure for Offline/LAN Mode