Half-Life cheat codes:
Start Half-Life using "hl.exe -console".
You may do this by modifying the windows shortcut properties for
Half-Life and adding "-console" to the end of the "Target"
(or file to run).
The /GIVE command works if you start the game with the -dev -console
parameter, and that the God mode cheat and map change cheat only work
with the -console parameter.
This will let you access the console using "~" key.
You may have to type "sv_cheats 1" in console first.
The following commands are available in console:
/GOD - god mode.
/NOCLIP - walk through walls/fly.
impluse 101 - all weapons
/MAP xxxx - go to map xxxx. Here's the maplist: