Kingdom Hearts is a game series that mixes both Final Fantasy and Disney together in one. I’ve only ever played the app since I never had a PlayStation when I was younger. The Kingdoms of Disney are being infiltrated by beings called the heartless. You enter those worlds as Sora who uses the keyblade to vanquish the heartless and their master. This is just an overall summarization of the series. The link above connects to Square Enix Kingdom Hearts main website.