There are some caveats. Blizzard is clearly focused on paid games, not free-to-play or giveaways. The Total War Saga: Troy giveaway saw 7.5 million people claim a copy within 24 hours, for instance. It’s also notable that other World of Warcraft expansions have come close — Cataclysm sold 3.3 million copies in 2010. Shadowlands is doing well, but its all-time highs aren’t that much higher.
We’d add that the COVID-19 pandemic may have played a significant role in uptake. If you’re keeping safe at home instead of heading out, you’ll have much more time to devote to hours-long raids and level grinding.
Even so, the revival is notable. World of Warcraft was one of the most popular games of any kind for a long while, but faded in recent years as rival online experiences and an aging engine worked against it. Virtually any other MMO would have been on the cusp of shutting down, if it hadn’t already. The question, of course, is whether or not this is sustainable. There’s no guarantee people will keep playing as the pandemic (hopefully) eases in 2021. If nothing else, this shows the Warcraft name still has a lot of value.