Version tested: PC
Portal is perfect. Valve's 2007 puzzle adventure – a short story about escape, in which the player must solve a series of spatial riddles with a gun that shoots doors – has a ruthless clarity to it, an economy of form and expression, that few games can match.
Its creators took one fantastic idea and developed it exactly as far as it needed to go and no further. They teased you with a premise that mocks your status as a lab rat running through their devious maze. They gave that mockery a cool, cruel and bitterly dry voice in GLaDOS, the arch AI that keeps you company in the game's pristine prison cells.
And then they lifted the curtain, just an inch, and let you look behind it. They almost surreptitiously slipped a neat parable of a story past you, sealing it with a punchline so resounding it knocks you back in your seat.
You can't call Portal heartless, it's far too funny a game for that, but it does have a heart of ice. It's so tight, so deliciously underplayed, that criticism passes through it like light refracted through a jewel.
Very little of this is true of Portal 2. It would be impossible to expand that haiku of a game into a 10-hour blockbuster (with a separate co-operative campaign for two players) without muddying those crystal waters. Inevitably, it's more talkative, the humour is broader, it contains some ideas that don't work as reliably, and the fiction's delicate relationship with the Half-Life universe is disturbed.
But the sacrifices are worth it a thousand times over. Portal 2 is a riveting and hilarious entertainment. It has Uncharted 2's easy way with a one-liner or action set-piece married to the intricate brain-teasing logic of the best Zelda dungeons. (Far from insignificantly, it's also a major video game that involves virtually no combat.)
Although its warped humour is miles away from Half-Life 2's oppressive tone, it is absolutely recognisable as that game's successor and equal, and thus the first full-scale Valve epic in over six years.
This is a new Valve, though, riffing on the cartoon comedy of Team Fortress 2 and the weathered B-movie pastiche of Left 4 Dead as well as its stock-in-trade cool sci-fi. That's clear from the opening, when you awake in a containment cell that's not an antiseptic glass cubicle but a simulacrum of a shabby 1970s-style motel room. The tutorial for the controls even contains a brilliant interactive gag at Valve's own expense.
Once again, you are Chell, the ponytailed woman in the orange jumpsuit who was GLaDOS's unwilling test subject in Portal. Many years later, a disaster appears to have befallen Aperture Science's labs and the clean white tiles of familiar test chambers are cracked and overgrown with vegetation.
You're woken from stasis by a chatty idiot of an AI called Wheatley, an expressive steel eyeball given verbal diarrhoea and an English West Country twang by Stephen Merchant (Ricky Gervais' writing partner on The Office). Wheatley begins as your guide and comic foil, a village-idiot version of Halo's 343 Guilty Spark.
When your sardonic, deadpan tormentor GLaDOS is rebooted, a strange and darkly funny psychodrama starts to develop between these disembodied voices and your silent avatar. Another commentator joins this intimate cast during an unexpected second act, which parodies BioShock while shedding some light on Aperture's past – but I really should stop there.
The script, by Eric Wolpaw, Jay Pinkerton and Chet Faliszek, is a riot. It's both shameless and devastatingly successful in its pursuit of belly laughs as GLaDOS gradually lets her bone-dry quips slip into withering sarcasm and Wheatley does that Britcom blend of surreal nonsense, self-mocking blather and slapstick. Portal was a sequence of great jokes, but Portal 2 is that rare beast, an actual video game comedy – and one of the funniest ever.
That's also thanks to the great voice cast. Merchant's prattle might chafe with some players, but I loved his deflating, humanising effect on Portal's cold brilliance. As GlaDOS, Ellen McLain manages the difficult task of taking a sociopathic and bitchy computer on a personal journey, and there's a splendid turn from veteran US character actor J. K. Simmons.
Valve's animators should also take a bow. Without much warning, they have revealed themselves to be some of the best in the business, delivering work of exquisite, movie-quality detail and timing.
Their greatest achievements are the two robots players control in co-op: this mute comic duo is like a mechanical Laurel and Hardy brought to life by Pixar. But even the robotics of Aperture Science's test chambers are lent personality and character, moving between slick, synchronised spectacle and the involuntary, violent tics of a madman.
Valve's virtual architects have long had an extraordinary gift for pacing and environment design, and it's in full effect in Portal 2. Artful details guide you through the space and the story, or hint at untold tales. The functional puzzle chambers are still the meat of the game, of course, but they're broken up with spells of up-tempo action or quiet exploration that give the puzzles room to breathe.
And those puzzles? There's nothing Valve can do to develop or perfect the first game's exploration of portals, whereby you use the two mouse buttons or triggers to 'fire' two doors onto certain surfaces, allowing you to teleport yourself and objects, or subvert the laws of physics and three-dimensional space to reach your goal.
So a number of new devices are introduced, the designers toying succinctly with each before moving on to the next. Sprung platforms called Aerial Faith Plates, and the Propulsion and Repulsion Gels that increase your running speed and jump height, are fairly standard-issue platform game mechanics given a great new lease of life by portals. Splattering gel like paint through cunningly-placed portals, or using portals to turn the faith plates into trampolines or orbital slingshots is a thrill that's both cerebral and visceral.
But the game's very best posers involve beams: laser switches, the Hard Light Bridge (a beamed platform) and the Excursion Funnel (a tractor beam that can pull or push you through the air). There's also a memorable moment of genius involving Conversion Gel, which allows you to apply portals to previously inert surfaces.
It's not until the very end of the game that Valve's designers dare to bring all these elements together – with gun turrets, cubes and switches, of course – in a mind-bending crescendo of ingenuity. Some chambers are vast, layered, cause-and-effect constructions that seem impossible before revealing a solution of such imagination, tactile satisfaction and devilish wit that you'll laugh as long and loud as you do at any of the jokes.
It's a shame it has to end, but it does, and unlike most games it ends very well, with a dumbfounding punchline and delightfully absurd coda. (Trying to recreate Still Alive in a new end-credits song was a mistake, though.) But Portal 2 is not over, because you can go on to enjoy several very happy hours of co-operative puzzling with a friend.
Co-op presents the most natural and intellectually terrifying extension of Portal's puzzle-platforming lexicon: two more portals. But if you're worried that these will simply be too much for your brain to handle, don't be. This mode is the perfect proof of the old maxim that two heads are better than one.
Valve realised in testing that it could set the difficulty bar much higher for co-op simply because talking through a problem will lead you more quickly to its solution. The result is one of the most satisfying and genuinely collaborative gaming experiences you can have with a friend.
(Digital Foundry will present a full multi-format Portal 2 comparison soon, but for now let's note that only the consoles offer split-screen co-op, while PC and Mac are arguably the best showcase for Valve's crisp visuals and precise controls. PS3 has the tempting bonus of cross-platform play via Steam and free access to the computer versions – but they all look great and play better.)
It's impossible to completely allay Portal fans' fears that this sequel might sully its pristine beauty. Although it's certainly no pushover, it's definitely more eager to please, and sometimes it's guilty of playing to the gallery. If you hate the idea that Stephen Merchant, comedy robots and tart fat jokes can exist in the same universe as Half-Life's Combine and Black Mesa, Portal 2 might offend you.
There's simply too much game here for it never to falter – but it hardly ever does. It's so generous and complete, so satisfying in each moment and in the whole, that a momentary lull, an overused mechanic or a cheap gag seem like trivial flaws.
Portal is perfect. Portal 2 is not. It's something better than that. It's human: hot-blooded, silly, poignant, irreverent, base, ingenious and loving. It's never less than a pure video game, but it's often more, and it will no doubt stand as one of the best entertainments in any medium at the end of this year. It's a masterpiece.
10 / 10