Kingdom Hearts χ, stylized as Kingdom Hearts χ[chi], is a Japanese role-playing browser game developed by Square Enix, BitGroove and Success, and published by Square Enix for web browsers as the eighth installment in the Kingdom Hearts series. Gameplay involves players navigating a customized avatar through Disney-inspired worlds fighting enemies, along with taking down bosses in multiplayer matches in competition with other teams. A version of the game for mobile devices called Kingdom Hearts Unchained χ was released as the ninth installment of the series in Japan in September 2015, and worldwide in 2016.