Last but not least, we have the Pneumatic Diversity Vent. Say your path is blocked by a roomful of turrets. Just stick one portal in front of the vent - a powerful vacuum - and one in the room. The obstacles will all be sucked out and safely disposed of. You can also use the vacuum to pull away weak walls and access secret areas, where plot clues will no doubt be left for observant players.
A WHOLE NEW WORLD
While the first installment of Portal was four hours long, the sequel's six new elements have given Valve a lot more scope for interesting puzzles. As a result, the game's much longer.
Plot also plays a more prominent role. The first game's storyline was never meant to be the star of the show but the black humour, sadistic personality of GLaDOS and subtle ties to the Half-Life universe ended up being as cleverly constructed as the tests themselves.
Of course, GLaDOS the rogue AI returns in Portal 2, but new characters also turn up, including a self-aware AI core called Wheatley who seems to be on your side, complete with a chirpy English accent.
Following up the smartest game ever made with something equally as worthy and groundbreaking is no mean feat, but if anyone can do it, it's Valve. The constantly evolving Source engine ensures solid visuals and staggering physics, and Gabe Newell said at E3 that Steam support will make the PS3 construct of the game "the best version on any console".
In addition, the game will feature a separate co-op campaign for two players. That means two Portal Guns in one level - can you imagine the mind-bending possibilities? First, we just need to work out how to portal jump to its vague 2011 release date...