That was the first feature added for JoiPlay, alongside the RPG Maker support. Especially since MV (and later MZ) games ran via HTML5/Javascript stuff. Also why TyranoBuilder games were also given support later on, because that also runs with HTML5/javascript stuff. All of which ran natively, while RPG Maker (XP onwards; though MV/MZ now need it nowadays for other modern dependencies) and Ren'Py games need their own separate module installed for it to run those related titles. Flash support is still in its infancy, so I don't have much else to say about it there, at the moment.