Imagine going through Portal without the computer to keep you company. Imagine stripping the story from Portal, and all you're left with is a mind-bending world to explore. A world where spatial relationships don't always match up with what the eyes see. Many reviewers describe this as an M. C. Escher mindfuck, and that's probably the most succinct way to put it.
The artistic look of the game is what attracted my attention at first. The graphics are so simple and clean. They almost feel homemade. Several spots reminded me of Mike Oldfield's Music VR (Tr3s Lunas), but that's just on the surface.
Rooms shift and move all around you. Walking down a corridor may lead to a dead end, but then you walk back the way you came, and now you're in a totally different room. Walking backwards down a corridor may take you to a completely different location verses walking forwards. It's akin to being in a maze that's constantly changing, but even that isn't accurate because the world never actually changes. It's all very logical, but totally unexpected. The game is full of impossible spaces and corridors that wrap back around on themselves without curving. It really does fuck with the mind, but it's all logical, and if you learn the game's internal logic, everything does make sense.
As if that weren't enough, you're then given a device that creates and destroys cubes, so now you have to get used to manipulating those. How you manipulate cubes depends on how far you've upgraded the device (I don't want to call it a gun). More areas become open to you, and they're full of wonder.
Took me about 8 hours to finish the game, and I never needed a walkthrough. It's superbly designed, perfectly balanced, and damn near flawless in every way possible. Antichamber is the most satisfyingly mind-bending game I've ever played. Everyone who likes games that are won by problem-solving and not by trigger finger needs to play this.