Kingdom Hearts χ (キングダム ハーツ キー Kingudamu Hātsu Kī), stylized as Kingdom Hearts χ[chi], is a Japanese role-playing browser game developed by Square Enix, Disney Interactive and Success Corporation, 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, Kingdom Hearts Unchained χ, was released in Japan in September 2015, in North America in April 2016, in Europe and Australia in June 2016.