During the game, press C then type marvin. Press C again to exit the menu then press F2 to drop a developer console:

Cheat Full - Player is Healed
Cheat God - God Mode On
Cheat God od - God Mode Off
Edit Abilities - A menu will appear; type the ability, then the value
Goto Waypoint [destination] - Teleport to destination entered after cheat
Toggle Time - Toggles Game Time
Toggle Inertiatarge - Affects player inertia
First Person - first person view