The Orange Box, universally hailed as the best value in gaming, has been flying off store shelves. Most Xbox 360 and PC gamers will buy Valve’s budget box set to play though the aging-but-still-awesome Half-Life 2 and its two episodic mini-sequels. But Orange also comes with another game set in Half-Life’s dystopian universe--the ever-innovative Portal.

Initially designed by a group of students from DigiPen, Valve saw their freeware school project Narbacular Drop (which hit the web back in 2005 and won considerable indie acclaim, including a finalist slot in Slamdance’s "guerilla gamemaker" competition), hired its creators and let them play with Source, the company’s proprietary game engine known for cutting-edge physics.

That came in handy because Portal is all about physics (and, of course, breaking the laws of physics) as you use a series of wormhole portals to navigate a mind-bending, four-dimensional puzzle game laid out like a first-person shooter.

You have a portal gun which was designed by the good folks at Aperture Science, Inc. (a rival company to Black Mesa, for you Half-Life nerds) who are using you as a test subject in their laboratory. Now, this gun can shoot interspatial portal entrances and exits to any room you’re in. It could be on the ceiling, the floor or a far-off wall. Then using gravity, momentum and creative logic (such as falling vertically to hurl yourself horizontally) you have to get yourself past obstacles to an elusive point B.

It sounds simple. It is not. The game can be more disorienting than wonderland, especially if you create an infinite portal loop that has you, essentially, chasing yourself down a rabbit hole. However, there is both rhyme and reason to it, if you can just suss it out and when you do solve a seemingly impossible puzzle, well, it’s even better than Brain Age at boosting mental self-esteem.

It is darkly funny. It is shorter than you would like. And it deserves legendary status alone for inserting "the cake was a lie" into the geek lexicon. Sure, it’s not the first game to make use of portals, but unlike a gory go-nowhere shooter such as Prey, Portal is an elegant, minimalist masterpiece.

Still need convincing? Try the free, 2D flash version of Portal.