This mod drastically changes the gameplay of Marathon!
Combat is much more fierce. This is like Marathon on steroids. Experience it for yourself.
*This mod establishes a new oxygen system: - You start with 2 minutes worth of oxygen (average human breath time.) -When you go into an environment in which you cannot breathe, you will start holding your breath. Be careful you don't black out! Holding your breath for too long makes you delirious, you know. - Luckily, if you make it to air in time, you can catch your breath and get those 2 minutes of air back. - Oxygen tanks now add tank oxygen to your total air capacity. When your tanks run out, you start holding your breath.
It is also possible to become delirious from being in a near death state.
Monsters and weapons are now more accurate and lethal, and travel at high speeds much closer to reality.
Physics are changed, especially gravity, which is more realistically amplified from the low-grav Marathon stock physics. NOTE: this may make some jumping puzzles unsolvable. Gravity has been changed to closely match that of Earth (on standard gravity maps).
This can certainly be improved upon, but for now, it's stable and it works.