Rocket League is a vehicular soccer video game developed and published by Psyonix. The game was first released for Microsoft Windows and PlayStation 4 in July 2015, with ports for Xbox One, macOS, Linux, and Nintendo Switch being released later on. In June 2016, 505 Games began distributing a physical retail version for PlayStation 4 and Xbox One, with Warner Bros. Interactive Entertainment taking over those duties by the end of 2017. Described as "soccer, but with rocket-powered cars", Rocket League has one to four players assigned to each of the two teams, using rocket-powered vehicles to hit a ball into their opponent's goal and score points over the course of a match. The game includes single-player and multiplayer modes which can be played both locally and online, including cross-platform play between the PlayStation 4 and Microsoft Windows versions, as well as cross-play between Xbox One, Switch, and Windows versions. Later updates for the game enabled the ability to modify core rules and added new game modes, including ones based on ice hockey and basketball. Rocket League is a sequel to Psyonix's Supersonic Acrobatic Rocket-Powered Battle-Cars, a 2008 video game for the PlayStation 3. Battle-Cars received mixed reviews and was not a major success, but gained a loyal fan base. Psyonix continued to support themselves through contract development work for other studios while looking to develop a sequel. Psyonix began formal development of Rocket League around 2013, refining the gameplay from Battle-Cars to address criticism and fan input. Psyonix also recognized their lack of marketing from Battle-Cars, and engaged in both social media and promotions, including offering the title as a free download for PlayStation Plus members on release, to market the game. Rocket League was critically praised, earning a number of industry awards, and saw over six million sales and 40 million players by the beginning of 2018. Rocket League has also been adopted as an eSport, with professional players participating through ESL and Major League Gaming, along with Psyonix hosting their own competitions through the Rocket League Championship Series (RLCS).