Every gamer has games that they consider iconic for them personally. Then there are the games that the industry see as real innovators or 'game-changers' (sorry). Finally, there are the games that achieve a critical mass in both arenas. To me, World of Warcraft fits that bill perfectly. I'm not alone there of course - our own Good Game has WoW at number 10 on its top 100 games of all time. Unlike many games in that list, it's still a current game with a new expansion out right now and a 10th Anniversary recently passed. So why has it remained so popular and what can other games and MMOs in particular learn from this particular ten year old? Here's three reasons I can think of:

Variety of content

If you haven't played WoW before, you may be unaware of just how big it is in terms of zones, continents and raid/dungeon content. With this week's expansion being the fifth (after The Burning Crusade, Wrath of the Lich King, Cataclysm and Mists of Pandaria), the level cap increases to 100. That's a lot of leveling time, although when the Cataclysm expansion hit there were lots of changes to quest lines to make leveling the first fifty or sixty levels a lot easier (and fun) than it used to be. The lazy can now buy a character that starts at Level 90 immediately.

It's worth noting too that Blizzard has put a lot of effort into offering different types of game play. There's still the usual PvE (quests and dungeons/raids) and PvP (beating the hell out of other players in set areas of the game), but there's now a fully-fledged pet battle system and the latest expansion revolves around building your own Garrison, something that was pivotal in the original Warcraft series of games. And don't laugh too hard at the pet battle concept. I was dismissive when it was added to the game but as a casual piece of fun it's very addictive.

There is a downside to the huge volume of content: returning users in particular can feel overwhelmed and be confused as to where they should pick up things again. That said, the user interface improvements and quest line changes of recent years make this less of an issue than it used to be. New users get the best experience they probably ever will have, but expect some adjustment time if you haven't played since Burning Crusade or Lich King. One last thing: kudos to Blizzard for recent changes that make it a breeze to get groups together for any old raid content across all of the expansions - I cannot tell you how much fun it's been doing achievement or gear runs over the past month.

I've actually leveled from Level 90 to 99 and a bit since the Warlords of Draenor expansion hit, and I have to say it's the most fun I've had in an expansion since Burning Crusade. The ability to dabble in Garrison-builiding is more addictive than I'd thought it would be, and the breadth of quest content means I'm about to hit Level 100 without having even been to two zones and having completed zero dungeons or other non-quest activities that give XP. There were definitely some teething problems in the first week but they are resolved now.

Solid backing by the developer

Any game that achieves longevity requires a developer that's willing to back it to the hilt and ensure its playing community stays on board. There are no shortages of MMO examples (League of Legends and World of Tanks are two that come to mind, both with larger playing communities than WoW), but Blizzard, I'd argue, has taken a unique approach. Being the behemoth it is, Blizzard has more than one successful franchise and it's been very careful in shepherding both Warcraft and Starcraft through their evolutions. There's not been large numbers of off-shoots and those that have been released have been very tightly linked to the franchise - Hearthstone is a great example. This focus has become even more evident given the recent announcement of the shelving of the next MMO they had in production, meaning that in MMO land they are very much sticking with Warcraft and Starcraft. The only brand new content was announced last month: a first person shooter called Overwatch.

Beyond that, Blizzard is stating its commitment for WoW for many years to come, with the next expansion slated for approximately a year's time and early work commenced on the one after that. It's not an MMO that's going anywhere, given its ongoing popularity. Which leads to the final point of recognition for WoW on its birthday.

Large player community

WoW is far from the largest MMO now, though it remains one of the most successful subscription-based games. At end of September there were 7.4 million subscribers, which was up slightly from earlier in the year. The Warlords of Draenor expansion released a few weeks ago has knocked the numbers up to over 10 million again but you can expect that to drop off once the expansion honeymoon period is over. Even so, that's one hell of a community of players who, on the whole, will have invested hundreds or thousands of hours on the game. You only need to look at some of the fan sites, knowledgebases and add-on developers to see how engaged people are.

That doesn't mean there's a shortage of opinions on the game though. Like any game of this size, there are plenty of opposing views on the game. WoW's progression, changes to game play, its user interface and how lore is being interpreted in the game are four common areas of debate. The one point of commonality is a passion for WoW overall and mostly it's exhibited in constructive ways - as long as you don't spend too much time in trade chat when playing.

Just to put any concerns to rest about me being a one-eyed World of Warcraft fan, I'm the first to admit the game is a long way off perfect. Even with the recent graphic improvements, WoW is showing its age. The cartoon look helps it age better than it otherwise would have, but even Blizzard must admit they have some work to do there still.

As far as gameplay, there are definitely MMOs out there that have better features in specific areas (check out The Secret World as one good example), but I'm yet to find anything that covers the number of bases WoW does.

I for one am fascinated to see how the evolution of WoW continues in coming years. If you haven't played WoW before, I'd argue it's still worth checking out, particularly given you can play for free for the first twenty levels. If you're a former player than drifted away, there have been enough changes to make a re-visit worthwhile. If you left the game hating it and vowing never to return, then I doubt anything I've written, or that's on offer, will change your mind.

So a very happy 10th birthday to WoW. May it see a twentieth, not just for its own sake but for the innovation and competition it creates in the MMO industry.

I'd love to hear your thoughts on WoW's ten years. Did you have a favourite expansion? Have you been on board the whole ten years? If you left, what was the breaking point for you? Where would you like to see the game go from here?

David has been writing on virtual worlds since 2006 and has been using them since 1993. Aside from being a WoW die-hard he also plays Star Wars: The Old Republic and The Secret World with a little Guild Wars 2 thrown in. You can contact him on Twitter at @dave_writer or at oceanicgamer.com.