Since Blizzard Entertainment added achievements to its massively multiplayer online role-playing game World of Warcraft in 2008, players have earned more than 13 billion of the virtual accolades — on average, about 8.7 million a day, said the game's lead content designer Cory Stockton.
Stockton spoke about Blizzard's approach to designing and implementing achievements in World of Warcraft and its many expansions at a GDC panel this week, explaining that the virtual rewards are more than just a "badge of honor" for players, they're also a pathway for players to explore new content. They can encourage players to adventure to new zones and revisit dungeons to explore them in different ways.
World of Warcraft's achievement design follows a set of rules, Stockton said. They should be optional, should not reward power leveling or bad gameplay (spamming spells, for example), should be simple whenever possible and extend gameplay.
"We don't want players to have the expectation that they think they need to get them," Stockton said, which can be problematic for some of the time-limited Feats of Strength achievements which reward players for playing WoW during a certain event or time period. "If you missed it, it's gone forever," Stockton said. "And it's really rough to have people stare at that list. So they don't show up until you actually earn them."
One of the more popular achievements in World of Warcraft is the "Leeeeeeeeeeeeeroy!" challenge: Kill 50 rookery whelps within 15 seconds. Close to 11 million players have earned that reward, Stockton said. One of the game's more difficult, most time consuming achievements, "Insane in the Membrane," has been earned by about 70,000 players.
Some WoW achievements have been earned only by a very small population of the game's millions of players — 9.6 million, as of Dec. 31, 2012 — like "Glory of the Pandaria Raider," a progressive achievement earned only by 342 players as of February.
Rarest is "Legendary Pet Brawler," an achievement added in Sept. 2012 with the release of Mists of Pandaria. Only one World of Warcraft player as of February, Stockton said, has managed to earn that, winning 5,000 player versus player pet battles.