The first achievement you'll get in Crysis 2 is a five-pointer, called "Can It Run Crysis?" It's a slightly self-satisfied reference to the game's PC-only predecessor, which was so technologically demanding that it became what amounts to an in-joke.
The domestic tech simply didn't appear to exist that could display the game at the highest quality settings. That said, it was a game set in a lush, open forest, that let you tackle broad objectives from numerous angles, and it introduced the world to the Nanosuit - the tool of a super-soldier, letting you sprint, punch sheds apart, and throttle Korean soldiers.
Crysis 2 has reassessed its priorities. It's narrowed its objectives, and spliced its DNA with a much more traditional, linear shooter. No longer in a jungle, but set in New York, the Nanosuit has picked up the slack - not gaining new powers, but becoming more flexible in the way you use it.
Escape for Alcatraz
You're Alcatraz, a man with a tequila hangover. He escapes death in the prologue, only to wake up in a new prison, the Nanosuit 2.0. From that point on, Alcatraz might as well not exist. He's a mute hero, operating on gravel-voiced orders grumbled into his ear by the surprisingly clued-up suit. The suit proves early on who's in control - it even freezes your body early on for a couple of mini-tutorials. If we can just invent a nauseatingly pretentious word for a moment, the Nanosuit is almost BioShockian in making you consider the limited nature of choice.
But what the suit takes with one hand, it gives back with the other. Its various modes let you carry out objectives in your own style. A tap on the right bumper makes you invisible, allowing you to flank, stealth-kill, or completely avoid your enemies. The left bumper springs you directly into armour mode, allowing you (in the easier difficulty settings, at least) to wade through the battle zone, kicking cars around like some kind of man-mental.
Less dazzling powers include power jumps, massive throws and sprinting - all of which drain the energy. Run out of energy at the wrong time, and you'll be visible, prone, and unable to sprint. To paraphrase: dead.
Crytek is extremely nervous about people using the suit in a variety of ways - and understandably so. The single-player campaign rewards the disciplined and the inquisitive - those who're determined to experiment.
It's rubbish - but entirely possible - to stealth your way through scenes that Crytek most likely intended to be colossal, fighty set-pieces. This weakness is something that it'd be perverse to blame on the player, but it's Crysis 2's version of "poking your head out and shooting someone else's head when it pokes out". All games can be played in a boring way.
Recognising this, the suit will occasionally offer you tactical options, overlaying waypoints on the map, and giving you a short description of what you can do there. Flank, Get, Use, Resupply, Stealth and Ambush are self-explanatory regulars - LedgeGrab, Explore and Observe are slightly more oblique clues. You can ignore them, but it's more fun to at least check out what's going on. The mostly-generous checkpoints mean you'll never suffer too hard for your curiosity.
When the aliens arrive, so does your reason to fight: the Seph drop Nano Catalysts which can be used to boost your suit. Armour enhancements, footstep tracking and stealth upgrades - they're more tweaks than game-changing abilities. Meanwhile, the AI can seem inconsistent, with nearby enemies being oblivious, and miles-away enemies spotting you the second you come out of cloak. So, keep an eye on the 'enemy awareness' meter - it's more important than it looks.