Things You'll Need
Instructions
Right-click on the Start button on the Windows task bar. (These guys must not have wanted us to cheat, 'cause they sure didn't make it easy. You will need to enable the developer's mode to input the codes.)
Click on Open.
Right-click on the Half-Life icon.
Click on Properties.
Add "-dev" (but leave out the quotation marks) to the end of the field that says Target or Cmd_Line. The line should then read: C:\Sierra\Half-Life\hl.exe -dev
Hit the tilde key (~) to access the console and enter the codes. Now you're running in developer's mode.
Type IMPULSE 101 to load up on weapons and ammo if it's just you and a crowbar against the alien invaders.
Type NOCLIP to enable your character to walk through walls, floors or ceilings if you know where you need to be, but can't figure out how to get there.
Type GIVE [item] if you need a specific piece of equipment to complete a level. The item commands include: item_airtank, item_antidote, item_battery, item_healthkit, item_longjump, item_security, and item_sodacan.