Valve, the creators of the Half-Life series, have developed what could have simply been a small-time component of a goodiebag. Instead, they have crafted one of the strangest, most thought-warping and mind-bending action puzzles I've ever had the sheer addictive joy of playing: Portal.
There is virtually no background to the game. You are given a "portal gun", a handheld device that can create a portal on any surface. You can create an entry portal and an exit portal, and you have to navigate a series of increasingly complex ways to use the portals and using every shred of physics, intelligence and rapid fire problemsolving you can. Challenge yourself and your friends: play Portal!
(warning: prolonged playing may cause some really bizarre nightmares!)