And it's a free switch to the classic mode for current subscribers, too. The vanilla game repurpose for what is now new architecture isn't just about plugging in old assets as the game has a lot changed in its 15 years as one of the most popular and successful MMORPGs of all time.

But that's exactly what this is: "a 15th anniversary, with celebrations in Battle for Azeroth to follow in the coming months", states Blizzard:

Grizzled veterans and hardy newcomers alike can now experience Azeroth as it was in its earliest days with World of Warcraft Classic, which is live starting today and included at no additional cost as part of everyone’s WoW subscription globally. World of Warcraft Classic has been a labour of love for Blizzard, and the result is an authentic re-creation of the pre-expansion game in its most feature-complete state, as it was during 2006’s “Drums of War” update (patch 1.12.0). Blizzard has continued to bring WoW Classic realms online around the world to accommodate the more than two million players who have created characters in anticipation of today’s launch, and will work to add more based on player population trends.

World of Warcraft, which has been played by more than 140 million players over the past 15 years,* has evolved considerably across seven expansions, with numerous features, enhancements, and quality-of-life improvements. In many ways, World of Warcraft Classic is more unrelenting and demanding of self-direction from players than today’s version of the game. Bonds among the community are paramount—activities like raids and dungeon runs must be organised collectively by players on the same realm, with the toughest challenges requiring 40 coordinated and committed souls to surmount.

Classic’s Azeroth is equal parts wonder and hazard, and its trials will push players to their limits. The Alliance and the Horde, in the midst of outright war, are made to reckon with forces whose powers transcend their own brutal conflict—including some of the most iconic and love-hated of villains of the Warcraft universe, like Ragnaros the Firelord and the Archlich Kel’Thuzad.

I personally haven't jumped back into the franchise beyond event hands-on opportunities for various expansions over the years, but I loved vanilla WoW, so this is something I might think about checking out

"It’s been a long time coming, but we’re overjoyed to welcome our friends new and old to classic Azeroth,” said J. Allen Brack, president of Blizzard Entertainment via press release. “The community’s excitement is infectious and deeply motivating—it’s clear they’re as thrilled as we are to relive the World of Warcraft Classic experience. We look forward to rediscovering its wonders and challenges together with them, starting today.”

Additionally, Blizzard has also put together a 15th anniversary in-game celebration event for Battle for Azeroth, featuring a max-level special raid against a number of some of the hardest raid bosses the team have created over the years. If you manage to complete the raid, you'll be awarded the "Obsidian Worldbreaker mount, inspired by the dreaded Dragon Aspect, Deathwing the Destroyer. And if you do login at all during the celebration, limited-time bonuses, a Lil’ Nefarian pet a special Achievement and, as the press release promises: "more".

Phew, that's a lot.

Is this something, if you still play, you could see yourself jumping into?