“Continent-building” is quite some job description – and that has been the task of the team of artists, programmers and designers behind the hit online game World of Warcraft for the past two years.

Wrath of the Lich King faces a daunting challenge: with 11 million paying customers playing for hours each week, this latest expansion needs to hold their interest for another couple of years.

To achieve that, Blizzard Entertainment has built an entire continent for players to explore, the icy northern land of Northrend – a vast and stunningly-designed realm that it will take players months to traverse and investigate.

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Blizzard are experts at this, but Northrend is their greatest achievement yet. The last World of Warcraft expansion, The Burning Crusade, introduced a distinctly science fiction theme. Here, the team returns to its roots in epic high fantasy. Players can expect to trek across wild tundra, exploring glaciers and fjords, before fighting their way through astonishing ice palaces and the enemy-infested ruins of ancient civilisations.

The colourful art style of World of Warcraft continues to be one of its strongest assets. Although small technical upgrades have been made to the visuals, it’s the art that keeps WoW looking fresh and beautiful – despite it being a four-year-old game. The pace of technological development usually renders older titles obsolete very quickly. Not so World of Warcraft.

Wrath of the Lich King’s sprawling vistas, quirky and memorable enemies and occasional wry visual humour are testament to artistic talent that lingers in the mind long after any technical considerations about the visuals are forgotten.

The new continent is the most impressive of Wrath of the Lich King’s offerings, but plenty of other new features are added. Players can expect to spend weeks or months progressing their characters to level 80 – the level required to face the toughest new challenges. Along the way, they’ll find many new abilities and talents that will change radically how each character class is played – especially in groups, where the dynamic has been rebalanced to provide a faster and more intense experience.

The expansion also introduces a new class, the Death Knight, the most ambitious yet. Described as the first “hero” class in the game, the imposing Death Knights are available only to players who already have high-level characters. With huge damage-dealing abilities and a unique play-style, they are likely to be hugely popular in the coming months – but they will also leave players scrambling to work out how to factor them into group or competitive play.

Few of Wrath of the Lich King’s features will be available to newcomers to World of Warcraft until they have ploughed through the content in the rest of the game - a task that could take months or even years for a casual player. Unlike The Burning Crusade, which introduced new playable races and content for newcomers, Wrath’s bounty is fairly heavily focused on existing devotees.

The appeal to those who haven’t already caught the WoW bug may be limited – but those already playing won’t want to miss out on Blizzard’s finest achievement yet. With Wrath of the Lich King, the Californian developer’s artistic, storytelling and gameplay crafting skills have reached another new pinnacle – leaving the cognoscenti wondering how the rest of the games industry is ever going to catch up.