Wheeee! The bit of Crysis 2's collapsed New York that I'm playing in has a makeshift slide – about 20 feet of wet, sloping concrete. If I sprint at it and duck, I launch my nanosuited mega-soldier into a high-speed bumslide. Hence the wheee.

There's an alien at the bottom, and he's blocking my path. The bastard, no one gets in the way of my bumslide. I'm going to kick him. I tap left mouse as I near the alien's lower body and boot his legs out from under him. Propelled by my strength-augmented shoes, he flies backwards, crumpling into a pile next to a wrecked bus. I should really go and make sure he's dead, but instead I run back around to the top of the slide. I combo'd a bumslide. Wheee!

It's about this point that I realise I'm actually saying “wheee!” out loud and three or four of Crytek Frankfurt's staff are milling around behind my PC, whispering to each other. One comes over. “Hey, so, that door over there is where you need to go.” I look at him with the pleading eyes of a man enjoying a bumslide, and he smiles wanly back at me. I go back to the top of the ramp one last time and “wheee!” under my breath.

I decide to try it his way for a while, and move into the next section. Crysis 2's New York is more organic than I'd expected: water flows from broken pipes to form makeshift rivers, grass and trees jut up from under the concrete. The fallen masonry has carved a path that enables freeform firefights – a choke point, followed by a wider area, corralled into another choke. Crytek call these sections 'action bubbles'. It's a formula the Halo series has experimented with to much success, but it doesn't immediately tally with the first Crysis's open manmurdering environs.

Past one doorway, and there's an alien with his back to me. I can't see how he didn't hear all that bumsliding commotion, but he seems oblivious to my presence – most likely because I've engaged my nanosuit's cloak and am now completely invisible. I've got a few options. I can empty a magazine into the base of his spine, but that's boring. I can move closer and snap his neck with one swift motion, but I'm saving that treat for later. Or I can punch a burnt-out car so hard that it lifts off and twats into his back, then hurl this trolley I'm holding squarely at his armoured skull. Did I mention I picked up a trolley? I was cradling it during the bumslides.

Guess which one I did? As the trolley bounced off my foe's head, it made a small clang. Turning round, I saw the Crytek guys. They were whispering again.

Crysis made you feel like an angry extension of the island you were dropped onto. The nanosuit was the star – letting players rise from the sea or the forest like a vengeful, invisible god and smash the teeth out of any ill-fated Koreans who happened to be milling about. Crysis 2 takes this empowerment, keeps it, and hones it. Five nanosuit powers have become two and a half: strength and cloak being the alternate states it can flip to, while speed is a sprint key and an increased jump. All drain your suit's energy, but combining something like cloak and speed means you get a limited window of invisible mid-air fun before you're dry on juice and visible again.

At the moment, the window to use suit energy successfully is tight. I found myself misjudging distances, flipping to cloak mode and launching myself at full speed towards a flock of enemies who hadn't seen me yet, only to fizzle into visibility a few feet from their position and face their combined fire. Waltzing into a combined onslaught felt imprecise, so much light and sound thunking into my suit's visor that I couldn't see an exit, let alone plan a defensive stand. Part of me wants unlimited energy to dick about in peace. I put this to Crytek's CEO, Cervat Yerli. “There was a version of that game about a year ago where we dropped energy to see what happened, but it felt wrong. We tried solutions to counter having infinite stealth – like if you run it flickers slightly – but there were still drawbacks.”

The increased vulnerability made me plan my rampages before engaging. To compensate and encourage that kind of behaviour, Crytek have introduced a tactical assessment mode. 'Magic goggles', essentially, the assessment view can be flipped on to note targets and track them as they move around the map and behind cover. After an acclimatisation period, it made my sprees much more focused and efficient – by the time I'd removed my armour-enhanced hands from the throat of one foe, I was already spinning to face my next target, rifle raised.

The tactical assessment view opens up another layer to the game, as Cervat explains. “The scan you get back makes three or four recommendations. You can mark the recommendations and they usually show you a way of taking advantage of a path you might not have chosen.” I tried this out on my fourth attempt at the first action bubble I played. On previous runthroughs, I'd gone for close-range firefights, but with a sweep of the tactical assessment view, I clocked a sniper rifle away from the action. Engaging cloak, I whizzed past a set of dimwitted aliens and hopped up to the ledge it was on. Shouldering it and hunkering down behind cover, I swept the field one last time to get a bead on my targets before pop-pop-popping three headshots off to kill them all without dirtying my nice new nanosuit.

This action bubble was one of the largest I played, yet thanks to the highrise architecture it felt tighter and closer to a standard FPS than Crysis's expansive setting. I asked Cervat if the games were comparable in level size. “In metres, they're going to be smaller, but they're about the same because we're pushing the height. Crysis was a sandbox, but it was a 2D game: you're just walking left, right, forward, back, and sometimes you jump. Crysis 2 is a voluminous experience.”

The switch brings its own challenges for the development team. “That requires awesome AI to take advantage of the volume, that traverses the buildings and jumps between different levels. It took 18 months to get an AI we're happy with that can follow you in 3D, and isn't scripted.”

My own playtime with the game didn't allow me to really push the enemy AI, but I did enjoy their realistic line of sight: my standard reaction to getting shot at was to duck behind a box, and pop my head quickly round one side, before turning cloak mode on and rushing round the other to blindside my confused opponents. If I could get a bumslide involved in the process, all the better. Seeing their confused alien faces staring at where I last was instead of tracking my ghost was reassuring – definitely a refreshing change from Crysis' omnipotent magic-men who shot you in the head from their perches on the moon.

The series' alien obsession continues into the second game, despite a less than favourable reaction to their floaty appearance in Crysis. This time around they're humanoid, and their armoured heads are topped off with fleshy dreadlocks, making them look like a Predator. When they move, they gallumph around the map, limbs jiggling – making them look like a Predator after a few pints when his favourite song comes on. There's currently a connection missing in close-range battles between player and aliens. Their armour dispels a lot of damage from your puny human guns, which makes gunfights into extended hosing sessions, repeated until the requisite squishy bit is exposed and the game tells them to fall over. It should be stated that this kind of thing is subject to heavy balance tweaks as the game progresses, but in eschewing foes as human as the first game's panicked Koreans, it's hard to feel truly connected to scraps.

Crytek are pushing that connection this time around, leaning so heavily on the game's story that they hired a proper book writer and everything. Richard Morgan – sci-fi author and the project's story lead – explained his take on Crysis 2's plot. “We're looking for a reboot as far as the console market's concerned. At the same time, we've got this history with the PC, and a set of fans we don't want to let down.” How do you do that, then? “The trick is to create enough stuff that goes back to the original game so fans will recognise it, go 'ah!' when they see it.” Not that Crysis had any particular resonance as a narrative experience – Richard charitably describes the plot as 'flimsy'.

But Crysis 2's main character is constantly clad head to toe in a buttockhuggingly tight suit packed with tiny friendly robots. I asked Richard how you make a man who looks like the inside of a bicep into a character. “The suit isn't a problem, because that's the FPS dynamic. You have to reflect everything back onto the NPCs. It was very important to me to have reactions from the NPCs to this guy in the suit, so you can see the questions they raise.” Crysis 2 seems keen to tell its story by reflection and osmosis, rather than stamping it in cutscenes, and that extends to the architecture. Graffiti around a choke point made reference to 'them' lying about where the game's alien invaders originate from. Intrigue! Delicious intrigue.

The 'series reboot' that Richard Morgan mentioned has been reflected in Crysis 2's multiplayer. It's been beefed up and farmed out to Crytek UK – the team who used to be Free Radical, the developers of multiplayer console shooter extraordinaire, TimeSplitters. That legacy shows. A short interlude – this is the bit where people who like to use words such as 'consoleification' should probably put this magazine down and start running around the room with their arms waving. For those still reading, I'll put it out there now: Crysis 2's multiplayer is already sharp and well polished, if completely different to the first game's cursory multiplayer addition.

Like the singleplayer level structure, multiplayer feels like Halo. Each player, as well as the standard suit armour/speed/ cloak suit skills, gets to choose two perks and two weapons, varying builds from sprinting shotgun bastard to invisible sniper bastard and all bastards in between. Despite the fact I was playing three-month old code, guns already felt right – the armour suit mode offered enough protection to make it noticeably worth using, even against heavy weaponry.

The game's Crash Site mode works like a king of the hill match, intertwined with the series' fiction: an alien drop pod whirrs around the map, hocking up gobs of alien junk that your team has to stand next to for a short time for some reason. Fancying myself a dab hand with a sniper class, I took cover behind a crate overlooking one of these objectives. With a corridor viewpoint and invisibility on tap, I was able to squeeze off killshots before rippling into the dark – until one of my opponents hurled himself from the top of a parking garage, fist-first, onto my exposed head. His ground-pound smushed me into the concrete, the perfect deployment of a multiplayer special skill.

Crysis 2 feels like what you'd get if someone explained the first Crysis when heavily sedated. The freedom and lethality of the first game are there in spirit, but they're given a more focused approach: Crysis 2 is much more driven, a sharpened point to Crysis's slug. The problem with following such a seminal title is the weight of expectation. My advice is to drop that weight, and just enjoy Crysis 2's bumsliding ride.