zBot are Valve's official bots for Counter-Strike 1.6. They were commissioned from Turtle Rock Studios, which was soon acquired by Valve Corporation™. The zBot bots are used in Counter-Strike: Condition Zero and Counter-Srtike: Source and are considered the best bots for Counter-Strike 1.6.
Controls: To control the bots, bring up the in-game menu while playing (the "h" key by default), or type the "+commandmenu" command in the console. You can also use console commands. The full list of commands is here:
Console commands for zBot
Installation:
Point the installer to the folder where your Counter-Strike 1.6 is installed.
For example: C:\Program Files\Counter-Strike 1.6\
For Steam: C:\Program Files\Steam\SteamApps\common\Half-Life\
Download zBot 1.5 [21 MB]
Source