[MMO juggernaut World of Warcraft has been shedding subscribers at an unexpectedly high rate since the launch of its latest expansion -- but what's the cause, and can anything be done to stem the tide? Gamasutra speaks to Blizzard, academics, and players.]

What is happening to World of Warcraft? In the months after the launch of Cataclysm, WoW's third official expansion, the game has lost almost 1 million players, dropping to 11.1 million subscribers from a peak of 12 million in 2010. The seven year-old MMO has been among the most successful video games in history, turning Blizzard into an essential piece of the biggest games company in the world.

In recent years the MMO model has changed dramatically, the pot of MMO gold has moved from a subscription model to free-to-play, with several games boasting player bases similar to, or surpassing, WoW's numbers. Where WoW once appeared to be king of an expanding empire of subscription-based games, it suddenly appears to own a market few compete in anymore. Indeed, with Cataclysm, even Blizzard revised its free-trial model, moving from a 14-day period to free-to-play until level 20.

Has WoW finally begun a slow but inevitable process of decline? Or is it simply changing, moving from one business model to a newer and sounder one? Is it possible to keep an MMO alive in perpetuity? Or do all virtual worlds have to die, no matter how big, glorious, and beloved they once were?

In With the Newb, Out With the Old

While Cataclysm famously destroyed the landscape of Azeroth, some of its most successful changes were to early game content. "The rework we did to the older content -- which was really showing its age -- was just huge," Greg Street, lead systems designer at Blizzard, told Gamasutra. "The quests flow better, there's not so much traveling all the way across the world, the rewards are just a little better."

Yet, fixes in one stage of the game can have unintended consequences in other areas, and with Cataclysm many of the changes to the changes meant for lower-level players have dampened the enthusiasm and sense of specialness for long-time players. Items, armor, and weapons that old-timers spent countless hours grinding, training, and raiding for have become increasingly accessible to newer players.

"One of the primary reasons I stopped playing was that I felt like so much of what made raiding interesting and fun was that elite end of the game where you have access to content that only a few people every get to see," Doug Thomas, Associate Professor at USC and co-author of A New Culture of Learning: Cultivating the Imagination for a World of Constant Change, said. "Systematically, I felt what Blizzard has done is taken their high-end game content and made it increasingly accessible to larger group of players."

"Even if you couldn't get the high-end Epics, you could get something that was pretty much equivalent through token systems. That kind of thing kind of eroded one of the core dynamics about what was fun about the game for me."

While many of these changes are off-putting to long-time fans, Blizzard is aware of the complaints. "We struggle with that all the time, it's huge," Street said. "We just don't have a lot of examples of games that have lasted this long and been this popular for so long to show the right way to do it."

"I think coming up with new mechanics and new systems is relatively easy, the problem is integrating it with what we already have. World of Warcraft today is so much more complicated than it was when it launched six or seven years ago."

While the joys of having an Epic item are diluted by the increasing number of ways for players to get them, the high-level game can still provide the special pleasures derived from gameplay itself. With new Heroic raids, new dungeons, and complex new challenges for experts to solve there could have been some off-set for the increasingly accessible loot rewards. But this approach comes with its own problems.

"The worst part of Cataclysm is the reward structure being all out of whack with content difficulty," Greg McClanahan, a long-time WoW player and frequent Gamasutra blogger, said. "Raids are much harder than they were in Wrath of the Lich King, but the rewards aren't significantly better than what you can acquire by queuing up for five-mans. On top of that, there's no longer any mystery about exactly which patch all of your gear is going to be obsolete."

"What this means is that you end up with a lot of people who are frustrated about wiping in raids, and there's not a strong rewards-based incentive to keep trying. That's precisely what happened with my own guild, and it drove us to stop raiding entirely, with a good chunk of people quitting or cutting back their play time significantly."

Learning, Leaning, Learned

Another long-term challenge for WoW, or any MMO that's survived as long, is competing against an increasingly savvy and capable player population. "The problem with the current structure of MMOs is that they're playing this kind of racing game with the player community based on expansions and creating new content," Thomas said. "They're never going to be as fast creating it as a certain element of the player base is going to be at defeating it."

"The amount of time it takes to do an expansion, or even to open a new dungeon, is astronomical in comparison to the amount of time it takes a high-end guild to get through it. Information from the high end guilds trickles out very quickly through the information network. It really only takes a couple teams knowing how to defeat the content to put it out onto various forums and wikis."

One of the ways to counterbalance this growth in familiarity is to gradually layer in new mechanics that extend the player learning curve. In some ways, this is the subtlest and most essential conflict in MMO design, to perpetually refresh the game's systems without altering its core.

"To entertain players and make them feel like there's reasons to keep playing we've expanded the systems, but those aren't free in terms of player comprehension," Street said. "You know, what does Reforging mean? What are Valor Points? What are Rated battlegrounds? What are Glyphs? We have all these new systems and sometimes we have to get rid of one system to make room for new systems."

"The achievement system we added in Wrath of the Lich King was huge because it gave us the ability to add a lot of new content that didn't directly compete with existing content. It wasn't necessarily another way to gain player power, and it wasn't a huge commitment for our artists to have to deliver more rewards or armor. But at the same time it gave players a lot of things to do."

The class system is another area where Blizzard has had success staying ahead of players while giving them interesting new problems to experiment with. "We're really happy with what we did with classes in Cataclysm," Street said. "We have 10 classes in the game now, but because each class can fill three different roles, it really feels like we have 30 classes."

"Some of them hadn't had attention in a long time and didn't feel right particularly at a low level. If you wanted to be a Retribution Paladin instead of a Holy Paladin that really didn't come into play until pretty high level but with the Cataclysm changes, right away at level 10 you can decide how you want your character to be and have him or her play the way they'll play later on pretty quickly."

Changes to classes also affect the social elements of the game as players not only have to readjust to their solo play but understand how it affects guild dynamics. "If you take the time to research the right build/stats/rotation and put a bit of effort into it, most players can play their classes pretty proficiently," McClanahan said.

"Raiding skill is a bit trickier because mechanics are constantly changing, but researching encounters also goes a long way, and having good reaction speeds and the ability to split your attention are also skills that get better with time and practice."

With so many different variables to worry about, Blizzard is in a strange position. After seven years of variation, adjustment, and new content is there a point where there are simply no new tweaks to add? Has player familiarity reached a saturation point?

"You're on an exponential curve in terms of learning, which means unless a challenge is virtually impossible you're not going to really be challenging your player base very much anymore," Thomas said. "I think there is a kind of asymptotic function happening at the very top end."

The End of the Expansion or The End of the World?

600,000 stopped playing World of Warcraft in the spring and another 300,000 have gone so far this summer. "I think a lot of people get bored quickly," Thomas Debeauvais, of UC Irvine's Department of Informatics and author of the paper "If You Build It They Might Stay: Retention Mechanisms in World of Warcraft," said.

"Even the most casual players will just raid a few times to try it, or maybe do it once a week. It's much more like companion playing. As far as the mechanics, they will eventually begin to lose interest, the problems stop feeling interesting or different, and they begin to stop caring."

Debeauvais's research was conducted in May 2010 and consisted of a survey of 2865 World of Warcraft players from the U.S., Europe, Taiwan, and Hong Kong. Almost all of the respondents had been playing WoW for at least one year and more than 70 percent had played for at least three years, itself a testament to the long-term commitment the game has inspired.

Debeauvais found that 75 percent of his subjects had stopped playing WoW for at least a month during some period of their play, and 40 percent had stopped for six months or more. "The funny thing with people who stopped playing [for more than six months] was that only half of them stopped paying for their account, even though they hadn't played in six months or a year," he noted. "I think there are many millions people fewer playing the game at any given time than the total number of current subscribers that you see talked about so much."

Blizzard has been sanguine about these player departures, attributing the issue to frequency of patches and new content. "For a long time now we've been trying to get to a place where we can release content a lot more frequently, that's something we've been working on for literally years," Street said.

"We think that instead of ebbing and flowing it keeps players more engaged because right when they're getting bored of old content we've got new content for them. We definitely know that three or four months after a patch comes out players feel like they've seen it all and they're ready for something new. We just haven't had time to crank that stuff out yet."

Some people are skeptical about this explanation. While there has been a traditional drop in player numbers following each WoW expansion, the period of decline has lasted longer and been larger following Cataclysm.

"There's something going on with the game," McClanahan said. "There isn't a lack of content in Cataclysm. The problem is the lack of strong appeal for anyone in particular. The gear doesn't carry enough psychological weight for the hardcore players, and the raids are too difficult for more casual players, especially relative to the rewards they provide. The last raiding tier was significantly nerfed in 4.2, but its rewards are now behind what casual players can acquire by doing 5-mans, so there's no incentive to raid older content beyond doing it once or twice just to see the new bosses."

For years, the strongest tie to WoW was a social one. For high-level players it became a kind of IM with avatars, a place where the relationships built over months and years of planning, learning, and achieving together could be give some ambient comfort. Five years ago the world of social networking was a relatively broad but shallow place, but things have deepened over the years and many of those bonds are now diffused across Facebook, Twitter, and Google+ is waiting in the wings.

"People play to be in contact with other people; doing something in the game is just another pretext to socialize," Debeauvais said. "Whatever the mechanics are in the game, the bigger draw is the guilds and the social network. It's like Facebook and Google+. Right now everyone's friends are on Facebook, but if your friends start moving to Google+ then you'll eventually move too."

If WoW's mechanics are at a saturation point where adding variety doesn't add new complexity, and its charms as a social network are waning in comparison to other platforms, is this the beginning of the end?

You Don't Lose Control, You Set It Free

"I don't think the original team that worked on World of Warcraft had any idea it would be going this strong for this long," Street said. "When we add a new class, system, or put out a new expansion we think, 'Well this might last for another 10 years. Is this something we're going to want to support far off into the future?'"

"It's probably going to be designers and programmers that we haven't even hired yet who'll be working on it then. As long as players keep playing it, having fun, and coming up with new ideas I don't think that there has to be an endpoint."

All MMOs have faced periods of dwindling decline, but there are many examples of games that have remained vibrant and rewarding from generation to generation. Part of why Chess and Go endure even today is that they let players take part in both the creation of problems and determining their solutions.

With its MMO, Blizzard has been in the business of designing vast amounts of problems, in the form of new quest lines, dungeons, boss encounters, and raids, for players to help one another solve.

But the tactics necessary to beat a dungeon or a particular quest are relatively fixed and, at the higher levels, exclude huge chunks of the player base from participating because of inadequate gear and attributes.

What if players were allowed to participate in creating their own dungeons, quests, or boss encounters? Or going further, what if the crafting and jobs systems were expanded to allow players a possibility to role-play in ways other than combat? What if FarmVille players could just as easily contribute to a WoW community, managing, harvesting, and trading crops, requesting new seeds from other areas, requiring some neighborly warriors to go out on an adventure?

"It would be a huge challenge to get something like that in place; on the other hand it pays dividends really well because it gives players something to do because they're spending time creating content and playing through each other's content, which is content that we don't have to develop," Street said. "We certainly got an awful lot out of the powerful editor that StarCraft II ships with. I don't know how long it would take us to develop something like that.

"It would be hard, but we have a lot of players that just want to feel like they're a part of the world, spend time in it and contribute to it at the end of the day. I think it would be really popular if that was something we were able to pull off. Minecraft is a great example because a lot of those players are showing off it's actually a creative medium and they're impressing each other with the tricks they've been able to figure out."

The idea of increased player control may be incompatible with certain basic expectations of the combat system, where the tolerance for randomization and unpredictability is low. "The idea of high end content that has a random factor to it, that's really controversial," Thomas said. "There was one boss in Caravan that dropped these big lava balls throughout the battle and they were randomized. I can't even tell you about the amount of bitching and whining from some pretty high-level guilds when confronted with a configuration that was unsolvable."

"They're perfectly willing to accept randomization within certain parameters, like how hard a boss hits. That can be a roll of the dice. Or there can be one of five configurations and you don't know which one you're going to get. That's just five more problems you have to solve and you don't know which one you're going to get. But the idea that there could be some sort of random element -- like life makes things unsolvable or unwinnable -- that is just patently unfair."

Could this aversion to the unpredictable and potentially unsolvable -- like the ever-present possibility of a draw in Chess -- be lessened if the game became less about upgrading abilities, gear, and combat and instead focused more about social role-play? Could WoW live forever if it evolved into not a social game, but a comprehensive world where social ties were the backdrop against which all types of gameplay -- combat, farm sim or hidden object storytelling -- could be experienced?

No, probably not. There's probably less to be gained from fretting about how to make WoW immortal than thinking about how to keep it rewarding for a little while longer. "We keep overhauling it, updating the graphics so it doesn't look too old," Street said. "Will the game still be here in five years? Probably. In 10 or 20 years? That's really weird to think about."

In the meantime, there will be new bosses, new raids, new dungeons, more quests, new loot, adjustments to what isn't working quite so while, and some new changes that will rankle people whole liked it the way before. And the world outside of Warcraft will move on, the people in it waiting for a more persuasive invitation.