Mainly comes from real-life experience. Some experiences are very unique, you found yourself entered a very different state of mind everytime you experiencing them, and you kinda love that feeling. That's always the moment I began to abstract it spontaneously. Though I always didn't realise it happening for a long time, until met a chance and it just surging up inside me, together with all questions I've been thinking for a while and trying to answer, all works I always love to read or listen or watch or play, everything all mixed up, and turns into an urge to make a game. It keeps looping in your mind, and you have to make it in order to stop that looping.