Type [Enter] and type in:

 -EMBIGGENME         - Invulnerability
 -CRAZYGUY           - Mana and all spells
 -WHOAH              - Fly mode
 -UBERLOAD           - Random level
 -SHOWFPS            - Show frame rate
 -CALCFPS            - Calculate frame rate
 -DEBUG              - Debug mode
 -BOUNDINGBOX        - Mark objects
 -CSWIRE             - Landscape ON/OFF
 -3DNOW!             - 3DNow! support ON/OFF