This was the game that introduced me to the Crysis franchise, and I've been a fan ever since.
I still remember the first time I laid eyes on this game at Blockbuster Video (You remember Blockbuster, right?) At the time, I had no knowledge about the previous games, knew nothing about Crysis 1, nothing about PC, I was a console peaseant and a huge Playstation fanboy at the time. All of my previous FPS experience had come from games like Call of Duty:MW2, Killzone 2, and Resistance: Fall of Man. All of those games were about running, gunning, non-stop action, twitch-like reflexes, switching weapons on the fly (because it's faster than reloading!), and all the pulse pounding action you'd expect from a shooter!
Crysis 2, I realised, to my surprise and later delight, was not of those types of shooters. Crysis 2 was methodical, tactical, and multi-faceted, loaded with verticality, cover mechanics, armour and stealth cloak modes you could switch to ON THE FLY, with tons of opportunities that the game showed you if you were looking, dedicated stealth mechanics like line of sight, hearing, tracking footsteps, tracking targets through walls with minimal distractin, stealth kills, on-the-fly customization of ANY weapon as long as it's in your hand, on-the-fly upgrade system, turrets you could rip off with your hands and carry like master chief, dedicated slots for explosive weapons, the entire game was like NOTHING I had experienced before.
I think a lot of fans give this game a bad rap because it's a drastic departure from the previous game, but the game has so much that it does well on it's own that I think too many people dismiss it without much thought. It's streamlined, sure, but it's done in a way that still retains what a lot of people like about Crysis in an easily digestible way and it showed me that not every great fps needs to be like COD or Halo, but can still stand out as it's own unique game.