Blizzard Entertainment is pushing back the release date for World of Warcraft: The Burning Crusade by a few weeks and it will no longer be available by the end of the year.

While the news may disappoint World of Warcraft enthusiasts, Blizzard president Mike Morhaime said the company would use the time to put "finishing touches on all of the new content".

First released in 2004, World of Warcraft (WoW) has been a worldwide phenomenon. A massively multiplayer online role playing game (MMORPG) set in the world of Azeroth - scene of all previous Warcraft games - World of Warcraft was released and has been maintained simultaneously for the Mac and PC. It's one of the very few MMORPG's to do so, so it's no wonder that WoW is popular with Mac gamers too.

In WoW, you assume the role of hero of one of several different in-game races, loosely aligned as either The Horde or The Alliance. You can choose from different character classes, such as Warrior, Priest, Shaman or more, then you go on quests to gain experience and retrieve special items and money, which you can then use to improve your equipment by purchasing from in-game vendors.

As an MMORPG, a key component of WoW is that you're sharing the game space with many other players as well. You can share quests to make it easier to battle high-level monsters.

Over the course of the past two years Blizzard has opened up new areas to explore in Azeroth and has added new high-level dungeons and "instances" to help keep veteran players playing.

The Burning Crusade is an entirely new expansion pack for the original game that gives players access to two new playable races, new professions, many new dungeons, monsters and items, and an entirely new continent known as Outland - the last remaining fragment of the homeworld the mighty Orcs hail from.

The Burning Crusade is presently in closed beta testing, which will continue while Blizzard is putting the finishing touches on the expansion pack.