How to create a Counter-Strike 1.6 FFA server

What you're looking for is called remote-console, or rcon. It's built right into the game; to use it, set rcon_password to the same value on the server (in server.cfg) and client (in the console), then type into the client-console rcon <command> for any commands you want to run on the server.

You can use rcon outside of the game, too. The most popular tool for this is HLSW.

The best option might be Condition Zero instead of plain CS 1.6

Z-Bot works still fine with the Steam Version:

• Download and extract the ZBot ZIP-File
• Copy all files (except liblist.gam and commandmenu.txt) to your ...\Steam\SteamApps\\..\cstrike directory
• In the Steam Game Library -> right click on Counter-Strike -> Properties -> Launch Options and add -dll "dlls\zbotcz"
• Now you can run the game