You wake up in a room without knowing why you're there - white walls, transparent doors, all very sci-fi - like cult horror film The Cube spliced with the video for Björk's All is Full of Love. A computerised female voice, one that you'll never forget, barks from some unknown origin, guiding you through the Aperture Science Laboratories test program. A portal appears, you walk through, but wait, something's up - you can see yourself entering it - or is that exiting it? Welcome to the mind-bending world of Portal.
You soon pick up the Aperture Science Handheld Portal Device, an instant addition to Half Life 2's Gravity Gun and Doom's BFG in that illustrious list of greatest game guns ever. From a first-person perspective you use it to create two portals - one to enter, one to exit, one orange, one blue - on walls, ceilings, the floor, whatever, as you work your way through to the exit of each of the game's 19 puzzle-tastic levels. Queue some of the most intense and masochistic level design we've ever seen, each more twisted and sick-inducing than the last. Portal is certainly not for the weak of stomach.
Portal works so well it's unreal. The game subtlety introduces you to its mechanics with a learning curve that's just right. You never feel so clueless that you feel like turning the game off. And yet the rooms never present too easy a challenge that you lose interest. Things start off quite simply - with energy balls bouncing off walls, cubes that need to be placed on button sensors to open doors and hard to reach switches that need to be flipped. But just wait till you get about halfway through the game - you'll be creating portals while flying through the air slingshot style, using gravity's momentum to propel you to ledges away in the distance, and dropping chairs on turrets that have some of the creepiest voice acting we've ever heard. It's all about forethought, timing and execution as things get more and more precarious. You'll even need to employ quick thinking and improvisation as threats present themselves without warning - and display a calm head as gravity automatically rights your point of view as you fly through portals placed on ceilings and walls.
An important thing to mention about Portal is that despite it being a single-player puzzler, it works wonderfully well with a friend or two watching, helping you work your way through to the main game's climactic end (no spoilers, but there will be cake). My flatmate and I started Portal about midnight and we both had a surprising amount of fun swapping the controller around, the two of us trying to work out a plan of action for each level. When we'd finally completed the game, we couldn't believe it was 2.30am - the time had flown by. We also felt a little sick.
Oh, about the end - Portal's ending is one of the most memorable we've ever had the fortune to experience. Again, no spoilers, but it left the two of us agog at its brilliance, hilarity and complete surprise. When it finished and we were brought back to the main game menu, the two of us just sat in silence for about half a minute, unsure whether what we'd seen had actually happened or was some kind of gravity-induced hallucination. Worth the admission price alone.
Which is effectively nothing, since Portal comes as part of the amazingly good value The Orange Box, which also includes cult FPS Half-Life 2, its two expansions and online FPS Team Fortress 2 all on one disc. While Portal is probably the lowest-key of the lot it's certainly the most interesting. Replay value is extended with six advanced maps (unlocked when you complete the game) that require exceptional skill to complete and challenges that award medals based on your performance. You'll also notice Valve's trademark developer commentary nodes dotted about the rooms once you've finished the game, which reveal interesting titbits on how Portal was put together. In the first one, Gabe Newell, Valve's managing director, says Portal is just the tip of this most mental of icebergs. The mind boggles at the thought of what's next for the Portal gun and us willing test subjects.
Flaws? It's perhaps a little short. Apart from replaying the game to listen to the audio commentaries, try the six harder maps and the challenges, we don't have much motivation to keep playing once we've seen that ending. Portal is tailor made for community-built rooms, either made available via Steam or through XBL on 360, or PSN when the game is eventually released on PS3. We're also making an official request to Valve to put the Portal gun in one of their FPS games - either in an update to TF2 or in a future episode of HL2. Portal's potential has been revealed - now is the time to realise it.
The simple ideas are often the best, and Portal, quite simply, is one of the best ideas for a game we've ever seen. It's fantastically realised, brilliantly executed, and had me wrapped around its computerised finger for two-and-a-half unforgettable hours. Don't let it become The Orange Box's forgotten son - this is gaming in its purest form.