Hit escape during the game. Pause menu will appear. Now hit tilde to show the command prompt. Enter any of the following codes. You wont be able to see the codes as you type them. You must re-enter them for each level.
Result - Code
God mode - god
All weapons - allweapons
Maximum ammunition - allammo
All weapons and ammunition - loaded
Flight mode - fly
Disable flight and no clipping - walk
No clipping - ghost
Stay underwater without damage - amphibious
Teleport to area currently looked at - teleport
Scale player size - changesize number
Restore default player size - changesize
Set player speed - setspeed number
Set maximum jump height - setjumpz
Set gravity - setgravity number
Set slow motion factor - slomo
Set camera to behind view - viewself Camera and pawn not rotated together when True - freecamera true or false
Toggle invisibility - invisible true or false
Possess a pawn of indicated class - avatar class name
Summon requested class - summon class name
Kill all pawns andenemies - killpawns