For the first time since it launched, World of Warcraft's 11.5-million subscriber base leveled off in 2009. But Blizzard says the MMO hasn't reached its peak yet.

Probably, although it depends a lot on Blizzard's ability to sustain the quality that fans have grown accustomed to, rather than relying on its popularity alone. Last week at "Tobold's MMORPG Blog," a reader posed the question, "Is WoW's success based on its player base or its quality? There are other games that are very good, even some excellent, so why is WoW this big?" Tobold tackled the question in a dedicated blog post, "Why is WoW this Big?", explaining why it's not a simple question to answer.

"Most people are completely unable to separate gameplay design from quality of execution," he wrote. "Thus if they are playing a game in which the gameplay is fun for them, they will say it is an excellent game of high quality, even if there are obvious flaws in the execution, like lag, bugs, and a bad user interface."

Tobold admits that WoW "has an excellent quality of execution," although that quality becomes totally irrelevant if players don't enjoy its particular style of "railed" gameplay, or if they become burnt-out from years of playing. He also cites WoW accessibility as a major factor in its popularity, noting Blizzard's revelation that 30 percent of its trial players exceed level 10 (a higher retention rate than most MMOs):

"How many 6-year old PC games do you know which still regularly hit the top ten of the PC games' sales charts? Apart from the problem in China, subscription numbers for World of Warcraft have held up steadily. Not because nobody ever quits WoW, but because there is still a steady stream of new players joining this game which balances the exodus of people who got bored with WoW. This is only possible because World of Warcraft is relatively newbie-friendly. Of course it is easy for the elitist jerks to pain [sic] accessibility as "WoW is dumb" or it "caters to the lowest common denominator". But actually the challenge level of the end game is completely independant [sic] from the ease of accessibility for new players."

Regardless of everything that made World of Warcraft the success it is today, the issue of whether there's still room for future growth depends on Blizzard's ability to continue offering incentives for existing, former and future players. That means the upcoming Cataclysm expansion should ideally serve as a launching pad for the "next era" of World of Warcraft, rather than a bookend for an aging MMO.

Fortunately, there is evidence to support this idea. Cataclysm is utilizing new graphics engine technology, core systems and gameplay mechanics are being completely revamped and many new features and abilities are being be introduced. The upcoming Real ID cross-game chat functionality will allow Blizzard's already-established fan community to interact in ways like never before.

And by plugging it all into Facebook and other social media, Blizzard is proving that it's willing to teach this "old dog" new tricks. If Cataclysm is a launching pad for the next few years' worth of new content and expansions, maybe it's not so hard to imagine that WoW still has yet to reach 15 million players, or whatever its "ultimate" peak may be.