Portal, probably more than any other game in the last five years, commands a huge sense of utter, undiluted love among video game fans.
Few would claim Valve's puzzle FPS ever outstayed its welcome; it presented a genius, accessible and yet often utterly baffling concept and then kept it brilliantly bonkers and masterfully inventive for three to four hours.
No lengthy cut-scenes, no tacked-on multiplayer or 'shocking' plot twists - just all the best bits of Valve's masterpiece design book, wrapped in one of the most charming game narratives ever. A bite-sized chunk of near-gaming perfection.
There's a good chance then you'd be extremely excited if we told you that the Half-Life developer had managed to extend the same no-filler experience to triple the length in a stunning sequel. And it has.
Though it's impossible to entirely shake off the feeling of familiarity (in single-player at least), Portal 2 is a head-flipping, physics-defying success - one of the best sequels we've ever played.
Like the original, imagination travels at 100mph, pacing is spot on and somehow Valve's managed to turn a bunch of inanimate objects into the most loveable video game cast in years.
And the script's hilarious; like, properly actually hilarious - not just for a video game, but for movies, tv... Any medium. Stephen Merchant and J.K. Simmons are on form here.
In fact, the more we think about it, the more we reckon (whisper it quietly): this could be the best Valve game since the last Half-Life. Gulp. But of course, it's not quite perfect.
Portal 2 is a story about you (or female lead Chell at least) and some robots - and there IS a story this time. Don't be mistaken into expecting Half-Life 3; the references don't go beyond a few mentions of Black Mesa (and in fact all Half-Life sound effects have been removed), but do expect strong dialogue, scenes of epic proportions and to eventually learn Aperture's darkest secrets.
Psychotic Aperture AI GlaDOS - who's surely now deserving of entry into the Best Game Characters Ever club - returns for the sequel, only this time she's contested by equally loud personalities in the form of Stephen Merchant's brilliant Wheatley, and Simmons (Spider-Man, Juno) as eccentric Aperture founder Cave Johnson.
The sequel takes place several hundred years after the first game, when Chell's woken by bumbling helper bot Wheatley in the now crumbling and foliage-filled Aperture laboratories.
Naturally you soon come across (and accidentally revive) your old foe GlaDOS, who swiftly puts you back to work "testing" with portals. Puzzles expectedly start progressively, initially restricting you to environment-set portals, then allowing you to set down a single hole etc...
Because of this forgiving start, veterans will naturally cruise through the opening sections, but thanks to GlaDOS's consistently entertaining banter you won't give a damn.
It's amazing how much personality Valve can squeeze out of characters that basically have no faces - even the inanimate objects in Portal 2, such as laser switches and hard light bridges, make sweet little beeps and noises that inspire instant infatuation.
GlaDOS's character progression is a joy to follow, as she progresses from bitter ("congratulations on having put on a few pounds"), to angry and eventually even finding a bit of heart.
Like the original though, behind the comedy robots lies some sinister undertones, and the Rat Man's drawings and destruction are constant reminders of the human-v-machines struggle.