Enter the console, then type in the cheats. Code Effect Crosshair 1 Gives you crosshairs Fly Flying mode (D=up C=down) Fov X Increases peripheral vision (where x is your field of vision) Give #x Gives weapon #x - 3=shotgun, 4=nailgun, etc.. Give C #x Gives x # cells Give H #x Gives x # health Give N #x Gives x # of nails Give S #x Gives you x # of shells Give R #x Gives you x # of rockets God God Mode Impulse1 Shotgun Impulse2 Super Shotgun Impulse3 Nailgun Impulse4 Chain Nailgun Impulse5 Grenade Launcher Impulse6 Rocket Launcher Impulse9 All Weapons Impulse252 Pentagram of Protection (30 seconds) Impulse253 Ring of Shadows (30 seconds) Impulse254 Bio-suit (30 seconds) Impulse255 Quad Damage mode Kill Commit suicide - restart level map e#m# Level Warp Map End Takes you to last level Noclip Walk through walls Notarget Invisible to enemies R_Fullbright 1 Everything is bright sv_gravity ### Sets gravity to ### Version Gives you version information Nightmare Skill Start in Normal skill mode. Go into the 4th episode but don't get into the time portal. When you fall out of the water, go to the console and type in "Fly". Go up , turn left, and enter the doorway... or... Step into the water but don't fall through. Swim all the way against the wall on the same side you enter the water (where the shield is in deathmatch). Now fall through and you will land on the rafter. Walk on the rafter right into the Nightmare entrance. If you have a hard time getting anywhere on the rafters, use the NoClip code and walk through walls until you find it. To be invisible to your deathmatch buddy but not the monsters, type: R_Drawviewmodel 0.