A Final Fantasy ttrpg. My searching pulled up a few fan-made ones but I didn't see one that was official. Don't even bother messing around with movement and whatnot. When you are in a fight you play it out jrpg style. FFX, FFX-2, and FFXII are my personal favorites but you could make a basic system and then put out a book for each game that covers it's unique aspects. Different spells, leveling/job systems, worlds, minigames, technology, etc.
Honorable mention to Mass Effect.