PC - Windows Cheats: Half-Life : Sven Co-op Cheats

Cheat mode:
Load game with the command line: hl.exe -dev -toconsole. Then, press ~ if the orange text on the screen does not disappear. During gameplay, press ~ to display the text prompt and type in sv_cheats 1 and press ~

Result - Code:

Toggle God mode - godmode [0 or 1]
All weapons - giveall
Toggle no clipping mode - cl_noclip [0 or 1]
Toggle opponents ignore character - cl_notarget [0 or 1]

Note: You can only use cheats when the maximum players is set to "2".