Yes, it is Single Player as well as Multi-player.
It story follows the same as Crysis but in this game, you control Sgt. 'Psycho' Sykes and shows what stuff he did when he was taking the 'other' route (I always wondered where the fool ran away when Nomad asked to cover him
).
You get to don the Nanosuit again. It has some super powers like Bullet-Proofing, Temporary Invisibility, Super-Speed and Super Strength.
There are many guns too.
Vehicles are also at your disposal and range from boats, cars, etc.
and ya, its a FPS (First Person Shooter).