Borderlands 2 is a first person shooter with RPG leveling. It's distinctive with it's cell-shaded graphics, over the top weaponry and characters.
We saw a demo of early Borderlands 2 gameplay where the player begins in a cold wasteland, and quickly comes across some ice-dwelling monsters. These showed off the improved enemy AI in the game: using their environments intelligently, enemies don’t simply attack, but will find objects to throw at you too and try to stay on higher ground. With humanoid enemies, this increased intelligence is even more pronounced - they work in teams to out-flank you, retreat when wounded and more.
All the battles in Borderlands 2 were reassuringly dynamic and dramatic, without feeling scripted. The range of weaponry is really varied, with the new use-once-and-throwaway-guns called Tediores looking really cool - they have ammunition in them, but you can also throw them as grenades, making them very flexible.
The mission demoed saw you teaming up with a female siren in two player co-op mode, to rescue Roland, a character from the first game. He has been captured by a large hovering robot, hiding out in a lair guarded by weaponized mining robots. Fighting through these as Roland is being taken away through the industrial complex, we saw enemy backup robots being fired in from a moon base, which looked really cool and emphasized the incredible scale. The moonbase can attack anywhere on the planet of Pandora, run by 'Handsome Jack', who is trying to violently bring law and order.
There was plenty of macabre, violent humor along the way, and the demo finished with the start of what looked like a big boss battle. The player was flung off a high damn structure by an enormous robot. Views from here, when there was time to look, were really impressive, and the huge landscape we could see is apparently all explorable in Borderlands 2.
Developers Gearbox were keen to make the point that they feel many game sequels are just 'content dumps', additional levels with no substantive changes, so they want to make Borderlands 2 a genuinely new game with real changes, and from what I saw, they are well on the way to achieving that.