Portal

Of the five stellar games collected in Valve's new Orange Box, Portal should make the most jaws drop. At heart, it's a puzzle game built around the "portal" mechanic, which lets you blast a pair of holes onto any two surfaces and teleport between them—for example, to get across a room, or drop on top of a high platform, or blip around an insurmountable barrier. Portal adds this to the standard repertoire of sliding platforms, tripable switches, and near the end, robotic gun turrets that whisper playfully, "I see you!" (When you knock one down, it adds, "I don't blame you."

That kind of detail is what makes Portal so intriguing. You're cast as a test subject in a strange, gigantic laboratory. An erratic, musical robotic voice leads you through a series of "tests," and the narration is hilarious and menacing. What's really going on here? What's a test and what's a malfunction? And what is Aperture Science Laboratories, anyway? Players' expectations, trust, and sense of free will are razed with grace and humor. Even when you spot a trick, you wind up falling for it—after all, gamers, like paranoids, are trained to pay attention to everything. (To get even more meta, Valve's Steam engine gathers data on everyone who plays the company's games: All those security cameras really do watch your every move.)

Valve's games are famous for their style as well as their quality. From the crisp visual design to the spare soundtrack to classy additions like a cameo by Mike Patton, Portal turns a novel game into an engrossing, mind-bending experience.

Beyond the game: The portal mechanism isn't new. The same designers used it in their student project, Narbacular Drop, and it's also a graphical representation of pointers—one of the first things most comp-sci students study.

Worth playing for: The hilarious credits sequence.

Frustration sets in when: Portal has been thoroughly playtested, and it offers several stumpers, but few moments that feel unfair: It's perfectly paced to teach you, lesson by lesson, how to think with portals.

Final judgment: Just as Valve's Half-Life 2 is the moody loner to Halo 3's high-school quarterback, Portal is smarter, cooler, funnier, and more sinister than almost any game this year.

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