Portal is a comedy puzzle game. A pretty black comedy, granted, but firmly a comedy. Most of the jokes revolve around you being lied to, killed, or thirsty to the point of delirium, but that won't stop you chuckling at least once per puzzle. In fact, that's usually the reason for it.
The puzzle part you're hopefully familiar with from the trailer or better yet, the 2005 prototype Narbacular Drop. You've got a gun that opens rifts in any wall you shoot it at, and once you've opened two, you can walk through one and come out the other. You're evidently a lab rat in an 'Enrichment Center' specifically designed to test your ability to use this device to navigate an absurdly hazardous obstacle course, led along by a lilting, broken-sounding synthetic female voice that rings out from tinny speakers.
It's set in the Half-Life universe, but that's about all anyone really knows about the plot. I did notice that the Enrichment Center has been daubed with graffiti by other test subjects in later rooms, which suggests some degree of rebellion. It's clear throughout that whoever set up the Center doesn't care much for the subjects: "Any contact with the floor," chirps The Guide, as we'll call her, "will result in an unsatisfactory mark on your test record, followed by death." An escape attempt towards the end of the game seems warranted.
But The Guide isn't the only voice you'll hear. The team have recently given the murderous turrets in the game voices - and even a range of personalities. They speak in the sweetest, friendliest possible robot voice as you come near ("Hello?") and even as they open fire ("Goodnight."). Some, the 'inquisitive child' personality ones, even remain genial when you topple them: "I don't hate you," they reassure as they spasm and shut down. Others are more alarmed: "Who ARE you?" one demanded fearfully, as I grabbed it from behind. I used her to block a torrent of fire from the next turret I encountered, and she cried out to her fellow: "It's me! It's me!"
What's surprising about the turret encounters is that they're not purely puzzles: most of them can be conquered with speed, quick-thinking and makeshift cover, and they're entirely freeform. In other words, they're combat. It's a refreshing change of pace from the thoughtfulness of the rest of the game, but if you do prefer to use only your brain, there's always a clever way of avoiding being shot altogether.
Expert Narbacular Drop players and wormhole physicists might worry that they'll breeze through Portal. But although it introduces its concepts to you gradually, it's a complex equation by the end. The later levels involve bouncing energy balls, moving platforms, physics puzzles, weight-triggered doors, and often require an impressive grasp of the subtleties of momentum. In fact, the last two chambers take 40 minutes or more each.
Then you've got the Challenge and Advanced modes. In Challenge you've got to get through the same series of rooms using either a) as few portals as possible, b) as little time as possible, or c) as few footsteps as possible: in other words, the shortest possible route. Advanced takes the hardest levels from the main game and adds more obstacles, hazards and complications until they become virtually impossible.
"It's all the things we'd like to torture our players with," says lead designer Kim Smith, "but they're just too cruel."
After that, what comes next depends on us. If the universal cry is for multiplayer, they'll take a whack at it. If players just want more of the same, they'll churn it out episodically. If lots of ambitious suggestions come up, they'll go back to the drawing board and start work on Portal 2. And if no one likes it at all, the team will split up and move onto other Valve projects. But that doesn't seem likely, somehow.