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

# Player 
     NumPad1: Invulnerable 
     NumPad2: Unlimited Health
     NumPad3: No Reload
     NumPad4: Unlimited Inventory Item Usage
     NumPad5: Ghost Mode (Invisible)
     NumPad6: Super Damage
     NumPad7: Fly
     NumPad8: No Clip
     NumPad9: Hover Player Higher
     Multiply: Hover Player Lower
     Add: Change Player Speed
     Separator: Increase Player Speed
     Subtract: Decrease Player Speed
     Decimal: Set Normal Player Speed
     Divide: Change Enemy Speed

# NPC  
     F1: Decrease NPC Speed
     F2: Increase NPC Speed
     F3: Freeze NPC
     F4: Set Normal NPC Speed

# Teleport 
     F5: Save Position Slot 1
     F6: Save Position Slot 2
     F7: Save Position Slot 3
     F8: Save Position Slot 4
     F9: Save Position Slot 5
     F10: Restore Position Slot 1
     F11: Restore Position Slot 2
     F12: Restore Position Slot 3
     F13: Restore Position Slot 4
     F14: Restore Position Slot 5

# Game  
     F15: Game Speed

Editor Options

# Player 
     Damage Multiplier

# Inventory 
     Slot 1 - Slot 30

Notes

Ghost Mode (Invisible):
You have to enable it before enemy sees or notices you otherweise it wouldn't work.

It might not work against some enemies.