When curious about what is behind a locked or closed door, use "The Eye" to see behind it. Get close enough that when you drop "The Eye", you do not pick it up when dropping, but it disappears. After that, look through "The Eye" and you should be able to see what is behind the door. This may require several attempts. Note: You may lose "The Eye" if you or the enemy destroys it. If that happens, you will be blinded for several seconds.
Use the following hint to hit targets at long range with accuracy without the sniper rifle: You need the binoculars and a gun with good shot accuracy, such as the pistol. Use the binoculars and focus the center of the viewer [ + ] on the target. After that, disengage the binoculars and the crosshair should be centered on the target. Fire away and you should hit. Note: The target should stay in one location or on your crosshair if moving forward.
Press T for the "Talk" feature, then activate the following cheats by entering the corresponding codes:
CHEAT FUNCTION - CHEAT CODE "Brian L. Goble is a programming god!" message - mpgoble "Brian L. Goble is a programming god!" message - mpscorpio "Jim Totaro is da man!" message - mptotaro 100 armor - mpnewcroward 25 to armor - mpward 300 health - mpreallynicenurse Add 25 to health - mpnicenurse All items - mpgoshopping All weapons - mpkfa Assault rifle - mpassaultrifle Beretta; enter again for dual weapon - mpberetta Bug buster - mpbugbuster Changes character model to Caleb - mpcaleb Changes our character model to Ophelia - mpophelia Changes your character model to Gabriella - mpgabby Changes your character model to Ishmael - mpishmael Cobalco laser rifle - mplaserrifle Extra weapons - mpbeansofcoolness Flare gun; enter again for dual weapon - mpflaregun Full ammo - mpammo Full health - mphealthy God mode - mpgod Hide coordinates - mphideme Howitzer - mphowitzer Increase speed - mpspeedup <1-5> Increase strength - mpstronger <1-5> Increased power; more gore - mpbeefcake Invisibility - mptakeoffshoes Kill all monsters on level - mpkillemall Life Leech - mplifeleech Minigun - mpminigun Napalm cannon - mpnapalmcannon No clipping - mpclip Sawed-off shotgun; enter again for dual weapon - mpshotgun Singularity generator - mpsingularity Sniper rifle - mpsniperrifle Sub-machine gun; enter again for dual weapon - mpsubmachinegun Tesla cannon - mpteslacannon The Orb - mptheorb Third person view, requires v1.01 - mpfollowme Triple damage Power-up - mpherkermur View coordinates - mpwhereami Voodoo doll - mpvoodoo Will power power-up - mpcarbonfiber Unknown - mpsuperzug