Activating this trainer

If not state otherwise below, press F1 at main menu.
Listen for 'Trainer Activated'.
Press desired hotkey. All hotkeys can be changed on the trainer.

Trainer Options

# Cheats 
     NumPad1: Allow Developer Menus

# Player 
     NumPad2: Invincible

# Weapons 
     NumPad3: No Reload

# Gameplay 
     NumPad4: Game Speed

Notes

Allow Developer Menus:
Toggle on and when you press ESC you can see the menu.  Also if this is ON when you enter a level, there is a menu to the right with many powerful features.