World of Warcraft: Legion sold over 3.3 million copies on its first day of sale, matching previous record sales for WoW expansions set by Warlords of Draenor and Cataclysm. The release of WoW's latest expansion also led to a surge in concurrent players during launch week, climbing to its highest point since the release of Cataclysm back in 2010.

"It's been a thrill to see players hunting demons, powering up Artifacts, and freely exploring all the new zones in Legion," Mike Morhaime, CEO and co-founder of Blizzard Entertainment, said in a statement. "We worked hard to make this the best World of Warcraft expansion yet, and we look forward to providing players with even more content as Legion's epic story unfolds in the months ahead."

Although WoW does not sport the same massive worldwide subscription numbers that it once did, these latest numbers are pretty impressive given the fact that the popular MMORPG was launched over a decade ago back in 2004.

Blizzard recently revealed at PAX West that the upcoming major content update - Patch 7.1: Return to Karazhan - will feature a re-imagined version of one of WoW's most popular raids.

"Players will explore a sprawling five-player Mythic dungeon, facing familiar foes from Karazhan's past—and encountering plenty of surprises and twists along the way," Blizzard said. "The update also features a new set of quests unfolding over multiple weeks in the fallen night elf city of Suramar, as well as a brand-new raid: the Trial of Valor, which sends players deep into the vrykul underworld of Helheim."

Earlier this week, the company released the free WoW Legion Companion app on both iOS and Android devices, giving players a new way to keep track of their characters and adventures on the Broken Isles. While one player has already managed to hit WoW's new 110 level cap in just five and a half hours, some eager players digging for some deep secrets accidentally unleashed a powerful hidden world boss named Kosumoth the Hungering.

In the sixth expansion to WoW, "Azeroth's defenders must embark on a dire quest to unlock the mythic secrets of the Broken Isles, master Artifact weapons of legendary might, and rally like-minded champions to their cause in their Order Halls. In this desperate hour, they must also strike a forbidden pact with the outcast Demon Hunters of the Illidari, fel-twisted disciples of the dreaded Illidan the Betrayer."