Continuing, another important part of the game is the weaponry.
To start, there is a weopan class called fusion rifles. The game offers no insight into how these guns work but the only assumption I can draw is that it has something to do with fusion. My theory is that there is some sort of nuclear energy generated by fusion and is somehow controlled and then fired from the wopen. There would be a lot of physics in the charging/splitting of atoms all in a short a series of short bursts.
There is also less exciting physics. For example there is a ton of projectile motion with the throwing of grenades or bullets. Also their is recoil in the guns. In this game you are a guardian, so I'd assume you are stronger than average but the odds are that there will still be recoil in the gun as a counter reaction of the projectile being launched (unless it's the ACR from MW2).
All in all, physics wise this is a pretty solid game. However, the story line is very week, the gameplay is repetitive, and the online can be pretty aggravating at times. That being said, Peter Dinklage is one of the voice actors, so you should buy this game.