Press the "t" key while playing and type the following codes: 

 

CatDebug All debugging enabled 

IAmACheater Cheats enabled 

GameDebug Game Debugging Enabled 

EngineDebug EngineDebugging enabled

Tricks:

Play as a Royal Canadian Mounted Policeman:
To play as a Mounty, press [Ctrl] + [Alt] + [Shift]. Then type in "Aye! Yo mother was a mounty!" and press [Enter].

Go through walls:
press [Ctrl] + [Alt] + [Shift] and type in: "dnclip" and press [Enter].