Start Half-Life using "hl.exe -dev -console -game gearbox.

 The following commands are available in console:

 IMPULSE 101   - Give all weapons and ammo
 GOD           - God mode
 NOCLIP        - Walk through walls/fly
 NOTARGET      - Invisible
 THIRDPERSON   - 3rd person view
 FIRSTPERSON   - Back to normal view
 MAP xxxx      - Go to map xxxx, where xxxx may be:

                 Single player:

                 of0a0 , of1a1 , of1a2 , of1a3 , of1a4
                 of1a4b , of1a5 , of1a5b , of1a6 , of2a1
                 of2a1b , of2a2 , of2a3 , of2a4 , of2a5
                 of2a6 , of3a1 , of3a1b , of3a2 , of3a4
                 of3a5 , of3a6 , of4a1 , of4a2 , of4a3
                 of4a4 , of4a5 , of5a1 , of5a2 , of5a3
                 of5a4 , of6a1 , of6a2 , of6a3 , of6a4
                 of6a4b , of6a5 , of7a0

                 Deathmatch:

                 op4_bootcamp , op4_datacore , op4_demise
                 op4_disposal , op4_gasworks , op4_kbase
                 op4_kndyone , op4_meanie , op4_outpost
                 op4_park , op4_repent , op4_rubble , op4_xendance

                 Hazard Course:

                 ofboot0 , ofboot1 , ofboot2
                 ofboot3 , ofboot4

 GIVE xxxx     - Give item xxxx
 GIVE WEAPON_X - Give weapon X, where X may be

                 357           - .357 Magnum
                 9mmar         -  9mm Assault Rifle
                 9mmhandgun    -  9mm Handgun
                 crossbow      -  Crossbow
                 crowbar       -  Crowbar
                 eagle         -  Desert Eagle
                 displacer     -  Displacer
                 egon          -  Egon Gun
                 gauss         -  Gauss Gun
                 grapple       -  Grapple
                 handgrenade   -  Hand Granate
                 hornetgun     -  Hornet Gun
                 knife         -  Knife
                 tripmine      -  Laser Tripmine
                 m249          -  M249 SAW
                 sniperrifle   -  M40A Sniper Rifle
                 pipewrench    -  Pipewrench
                 rpg           -  Rocket Thrower
                 satchel       -  Satchel Charge
                 shockrifle    -  Shock Rifle
                 shotgun       -  Shotgun
                 snark         -  Snark
                 sporelauncher -  Spore Launcher

 GIVE AMMO_X   - Ammo for weapon X, where X may be

                 357          -  .357 Magnum
                 9mm          -  9mm Assault Rifle
                 9mm          -  9mm Handgun
                 crossbow     -  Crossbow
                 ???          -  Desert Eagle
                 ???          -  Displacer
                 egonclip     -  Egon Gun
                 gaussclip    -  Gauss Gun
                 556          -  M249 SAW
                 762          -  M40A Sniper Rifle
                 rpgclip      -  Rocket Thrower
                 buckshot     -  Shotgun
                 spore        -  Spore Launcher

 Easteregg:

 Approach the Boss of Opposing Force to hear backwards audio composed of
 the phrase "To win the game you must kill me Randy Pitchford" when
 played correctly. Randy Pitchford is the leader of the development team
 at Gearbox Software.