Why would you sell your IP's to Mistwalker ? , just as Enix never directly developed games , they contracted the likes of Quintet ( makers of terragama) and others to do it for them , with themselves then going on to own and publish the IP or in the case of Star Ocean co -ownership, We have Mistwalker involved in something similar except as a third party, take the case of Lost Odyssey , MS takes on Enix's role but instead of a Quintet doing the whole game development , Mistwalker does the planning and has FeelPlus do the development , so in effect they operate as a creative third party , So if Square-enix wanted to use them all they have to do is contract them to do the planning for one of their IP's.
Research shows Video games help make you smarter, so why am I an idiot
