World of Warcraft: Cataclysm

The change is exciting. To keep this now-ageing game fresh, it's necessary. But for a long-time player, seeing zones which have been scored in the memory changed for good and never to return is also a bit of a wrench. "We're trying to tap into that to some extent," says leads systems designer Greg Street. "The Cataclysm is supposed to be a little bit scary. You know, it's a big time of change, and so we want to make players curious, maybe even shock their system a little bit that in some cases things are so dramatic."

The new 80-85 zones are no less dramatic. In the demo in Blizzard's cinema, we're flown around Uldum's monolithic, fantasy ancient Egypt where the Blood Elf Reliquary, Dwarven Explorers' League and other less reputable looters are hoovering up the secret history of the Titans. Deepholm is a giant enclosed sphere in the centre of the world where Deathwing lived in exile, its vast central spire and ceiling raw and torn from his explosion back into the world. Orc airship Orgrim's Hammer lies wrecked on the ground. It's midnight blue in here, and studded with bright crystals, as otherworldly as anything in Outland.

Later we get to try two of the other new zones ourselves. Mount Hyjal, entered from Winterspring, is an immense, tortured spiral of rock with the World Tree Nordrassil at its summit and Sulfuron Spire, a robust flame-elemental fortress with a giant Sauron-style eye, at its base. But it's Vash'jir that is the biggest departure of the lot.

Taking a boat from Stormwind, we fall victim to a sea monster and drown, whereupon a Draenei saves us and grants us the power of water-breathing and increased swim speed - because this is WOW's first wholly underwater zone. You can walk on the sea floor here, and eventually acquire an underwater mount. It's all done in bright, creamy Caribbean colours, with forests of giant kelp and luminescent coral reefs surrounding the mysterious lost cities of the Naga. It's breathtaking.

Finally, there's just enough time to start characters Cataclysm's new races - Goblins for the Horde, and werewolfish Worgen for the Alliance - and punch through the first five levels of each. Starting where the Death Knight class introduction from Lich King left off, these are no ordinary WOW questing zones, but riotous, event-packed mini-adventures that almost mock the traditional rat-punching humble beginning of MMOs.

In fact, in the case of the Goblins, there's no "almost" about it. In Blizzard's cartoonish take on GTA, you star as a would-be trade prince in the dirty, congested Goblin city of Kezan, running over citizens in your hot rod, torturing workers, beating up debtors, playing sports in a robot suit, buying bling and entertaining guests at a poolside party. The humour's coarse but irresistible. The Worgen starter goes for straight high adventure, casting you as a (soon-to-be-un) human fighting off a Worgen invasion in the streets, lobbing bombs from horseback, manning cannons and battling through alleyways in a John Carpenter-ish last stand.

Both feature stunning use of Blizzard's phasing tech that allows the world to change and events to pass naturally around you as you move through quests. The transitions are much smoother and more frequent than anything in Lich King, and mark a final end to the illusion-breaking, static Groundhog World of the MMO, locked in one moment of time. It's too much to hope that they'll be applied across the entire game, but still, their frequent use would make all the difference.

In fact, while they're not going to be "Worgen and Goblin awesome" in lead world designer Alex Afrasiabi's words, the starting experience for every race in the game has been revamped - as he explains in our interview, Blizzard soon realised that it was the earliest levels that would need the most attention in Cataclysm's content clinic. But it's not just the quests you do as you level, but the levelling itself which will be radically changed.