A favourite new addition is the light beam walkway which can be passed through a portal to act as a walking surface or a turret shield. As seen at last year’s E3, there's a repulsion gel, propulsion gel, aerial faith plate, pneumatic diversity vent and more. Valve has, however, spiced things up with the addition of a few new tools players can manipulate to assist them in the mind-boggling puzzles they face. In the words of GLaDOS, “Speedy thing goes in, speedy thing comes out”. The basic Portal gameplay laws still apply: Object goes into one portal, and out the other. The dual-portal gun from the first game is, of course still the weapon of choice. But the dialogue never feels forced, and it's always a moment of levity in situations where the atmosphere can definitely seem scary. GlaDOS even has a few fat jokes up her robot sleeves. It’s almost a bit of overkill - nearly every line uttered in the game is intended to make players laugh.

In fact, they’ve turned the funny dial to 11.

Portal’s famous humour remains intact in the sequel. I won’t spoil the game by divulging too much, but I will say this: Portal 2 features a couple of major plot twists and opens up the world significantly Chell is not just confined to the Aperture Science facility, and the game is better for it.

But this time around, she's not alone - while isolation was a big part of Portal 1, Chell now has the loquacious Wheatley, one of GlaDOS’ discarded personality cores, to assist her intermittently. The game's protagonist Chell, rudely awoken from her slumber/coma at the game's start, is still stuck in the Aperture Science nightmare. There were familiar sights - like the glass corridor which leads into GlaDOS’ chamber - but Portal 2 is built on a much grander scale, and everywhere looks so much bigger. Moss-green overgrowth and ailing machinery now fills the facility in Portal 2, and my first thought when I saw the place was how different it looked from the original. The sterile setting was partly what made the first Portal game so memorable - the eerie silence and clinical cleanliness of the Aperture Science laboratories made it all the more jarring when GlaDOS decided to bake you alive, for example (presumably to make that elusive cake she kept promising). She talks a lot more now, and it's mostly about how much she hates you. Having relived her demise repeatedly in the period between the two games, GlaDOS' behaviour has evolved from passive-aggressive to bitter and blatantly sadistic. Portal 2 is set in the dilapidated Aperture Science facility, and the homicidal GlaDOS - the resident bipolar artificial intelligence - is Still Alive (I’ve used this joke before, but it never gets old). Long ago, on a PC far, far away… in Australia

Should i play portal 1 before portal 2