A virus is a microscopic organism that can replicate only inside the cells of a host organism. Most viruses are so tiny they are only observable with at least a conventional optical microscope.
Recognized by the Guiness Book of World Records as the MMO with the longest play time per player, and easily the oldest game on this list (launching four years ahead of World of Warcraft, way back in 2001), Runescape deserves mention because it's one of the most updated and popular games of any kind on the planet.
The Elder Scrolls Online, also known as The Elder Scrolls Online: Tamriel Unlimited, and commonly abbreviated as ESO, is a massively multiplayer online role-playing game (MMORPG) that was announced in May 2012 and was released for PC and Mac on April 4th, 2014. It is the eighth game in The Elder Scrolls series.n June 9th, 2015, the game was released on PlayStation 4 and Xbox One. Developed by the team at ZeniMax Online Studios, The Elder Scrolls Online merges the unmatched exploration of rich worlds that the franchise is known for with the scale and social aspects of a massively multiplayer online role-playing game.