Dr. Aiden Krone skin:
To unlock the Dr. Aiden Krone skin, go to "Options" > "Multiplayer" > "Model" and press left to highlight Dr. Aiden Krone. Press triangle and enter "RXYMCPENCJ" to unlock the skin in multiplayer mode:
Final Boss strategy:
After destroying one of the gigantic sentinels guns with the Pulse Gun, escape the the raining artillery from Dr. Krone by going into slow time and moving to the far right corner. Jump up on the platform. Run to the corner on the right where you will take no damage from the raining artillery.
Change running, jumping, and gravity:
To alter running, jumping, and gravity in single-player mode, go to "System Link" > "Host". Set the movement to "Very Fast", the gravity to "Very Low", and jumping to "Very High". The game will fail when attempting to host it. The settings will be retained when starting a single player game.
Blocking the wind fans:
When you face the first wind fan after coming from the tunnel, there are four platforms around the fans. On any platform facing towards the wall, reverse time. Do not let your time energy disappear completely. Before the time energy is completely gone, stop time and go over to the platform.
Look at your footprints (on cement or somewhere clean) after killing someone or stepping in oil or mud. It will read "Atrox" near the top.