Far Cry: Instincts is possibly the best xbox FPS to date.
You start out with only a knife to help you untill you take down some guards and take their 9mm. You can do various attacks. Backstab is one of the more fun ones. That is if you ever get the chance to do it!
One of the missions require you to search for Val, your teammate. You find her and help her out by sniping people so that she can safely reach the boat. You suddenly feel a sharp pain in your neck, and pass out. You wake up in this basement place chained to a metal chair where they test experiments on you. This guy is telling you what happens down here and yet again, you passout. You awake again in this little area in the back of this truck. You don't feel right. You feel diffrent. Then you find out you have claws. Your skin is diffrent. You're beast like.
Now you have all these powers! Claws, Super Run, Smell, Jump, Thermal Vision, ECT.
That is just a taste of what you will come across in Far Cry: Instincts. Go buy it. It is sure to be Xbox GOTY.