An important factor in World of Warcraft's 20-year player retention has been the addition of fresh content in the form of expansion packs, like the highly awaited Wow the War Within, which will soon be released.
Despite being 20 years old, World of Warcraft is the most played MMO worldwide, with 1.32 million daily players, according to MMO Populations. It definitely affects online multiplayer games like Final Fantasy XIV and gaming in general.
