Is straight Fate Core any use?
It occurs to me that I think I said something recently about FATE `always requiring shaping', so maybe I can clarify that a little bit, too.
Core FATE is very.. I would say generic? The Skills and Stunts are meant to work across genres, at least more or less, while Aspects are just so totally open.
So when I say it needs a lot of shaping, I'm not talking about house rules or even rebuilding the Skill list. I just mean the way you use everything in it, has to be.. angled, towards the game you want to play. The way that many Skills are going to apply might be different -- like, does Burglary include disabling electronic locks, or just picking mechanical ones? The Shoot skill can apply to bows and crossbows, six-guns, or laser pistols... or all of them, depending on what's available and logical in your game. Contacts in one game might hook you up with the head of the Thieves' Guild; in another, you can call the head of a local go-gang `chummer'.
Characters have to - but also should naturally - pick Aspects that make sense. "My Laser Gun, Bessy" isn't going to fit in most medieval-fantasy games, but, duh. Like Skills, something like "Obsessed with the Occult" might be totally reasonable in any game, but is going to mean very different things in a Fantasy, Horror, or Science Fiction game.
You can use FATE Core straight out to play quite a number of genres without any changes to the system. Because the system always needs, as I say, shaping, that shaping is built right in to the system.