By Phil Elliott BBC Radio Five Live

Millions spend hours in the virtual Warcraft world

If you have played games online in the last year or so, then World of Warcraft is a name that has been hard to avoid.

Blizzard's stunning MMORPG (massively multiplayer online role-playing game) has swept all before it, breaking various genre records and notching up more than 5.5 million regular players in the process.

It has been a meteoric rise for a game that was expected to do well, but arguably not this well.

"It's pretty surprising to us," said the game's lead producer, Shane Dabiri.

"I don't think there was ever a time when we said we'll make five million subscribers after one year of being live."

The rise of broadband and the higher average age of gamers have contributed to Warcraft's success, but the accumulation of so-called casual gamers is the key.

Such players may be dabbling in online games for the first time and World of Warcraft's accessibility manages to draw them in, and persuade them to stay.

"The casual gamers come from every aspect of the gaming community. Some of them have an hour to play at night, some of them have more, and we need to make sure that the elements in the game appease those type of tendencies."

Dungeons to explore

However, for anybody that has successfully taken a character to the maximum level, they will know that the range of available activities begins to limit significantly.

The world of Warcraft has so much more to give that I think we could be expanding it for five, 10, 20 years to come Shane Dabiri Blizzard

To this end Blizzard have recently announced some additional content to offer more to these players .

"We felt it was important to give them some more to do, and giving them the ability to upgrade their existing equipment without having to spend four or five hours in a raid with 39 other people was important to them."

Looking to the future, Blizzard announced late last year that an expansion was under development, called The Burning Crusade.

Although it will cost an additional amount to buy it will add a significant amount of new content to play through, including flying mounts, new races and a new profession.

As part of this expansion, the highest level a game character can achieve will also be raised from 60 to 70, prompting fears among the community that their current top end gear will become obsolete, and that the hardest dungeons now will be far easier in the future.

"Increasing the level cap will definitely give players a lot more power. It's very similar to the current level 60 players going back to a level 40 dungeon.

"But the point is that there are new challenges out there, there are new dungeons for them to explore with even better items and even better gear."

More to come

Effectively anybody who does not purchase the expansion will be cut off from the new content and will therefore fall behind those that do.

The Burning Crusade expands the world of Warcraft

Whilst this might seem like a cynical business plan, it is likely that The Burning Crusade will sell extremely well because gamers are so hungry for more.

When it comes to the long term future, there will no doubt be further expansions and content patches to come, but how long can the World of Warcraft success story last?

"It's one of those things that's difficult to say. If it was up to me it'd last forever, but as long as the players want to stay and enjoy themselves, we have no limit to the number of stories we want them to experience," said Mr Dabiri.

"The world of Warcraft has so much more to give that I think we could be expanding it for five, 10, 20 years to come."