When Elder Scrolls Online launched back in 2014, I didn’t find much exciting about it. It was an MMO that stuck close to the template established by World of Warcraft, rather than the Elder Scrolls games that preceded it. Elder Scrolls Online wore the clothing, but it lacked the heart and soul, and fans were open with their disappointment. Five years later, Zenimax Online’s exploration of Tamriel is celebrating 13.5 million players, up 2.5 million from the previous year. It’s a fantastic turnaround, one which Bethesda attributes to the players that kept enjoying the game.
Source: N4G PC "We Like Where We are Right Now": ESO's Developers on Player Milestones and Elsweyr's Future