Launched in 2009, League of Legends is a multiplayer online battle arena video game developed and published by Riot Games. It is inspired by Defense of the Ancients, a custom map for Warcraft III and is currently a stand-along free-to-play game in its genre. In the game, two teams of five players battle in player versus player combat, each team occupying and defending their own half of the map. Each of the ten players controls a character, known as a ‘champion’, with unique abilities and differing styles of play. During a match, champions become more powerful by collecting experience points and purchasing items to defeat the opposing team. In the game's main mode, Summoner’s Rift, a team wins by pushing through to the enemy base and destroying their ‘nexus’, a large structure located within it. The game is often cited as the world’s largest Esport, with an international competitive scene composed of 13 leagues. The 2019 League of Legends World Championship had over 100 million unique viewers, peaking at a concurrent viewership of 44 million, with a minimum prize pool of $2.5 million.