IC: Emerging Threats Unit
The more active your players, the more likely it'll survive. All too often players come to a game and then find that it's not for them and they beg off.
I'd suggest you all create the game together. That would also tie in with Create Advantage and the players creating facts for the setting. Some GMs want more control than that, but I've played in a FAE game where players were invested and it was a blast.
For the more "magic-y" elements, you could look at Fate Codex v2n2 for the Corruption rules. That might be a nice dark element for humans tampering with unknown forces. The mechanics, if you don't have the Codex (which I highly suggest) is that when you Succeed at Great Cost, you can choose Corruption for one of your Approaches, which then changes, e.g. Forceful becomes Aggressive. When all your Approaches become Corrupted, you become an NPC (as you've completely gone over to the Dark Side, if you will). You can redeem yourself, naturally, so it's not a one way street, and, of course, there's more to it than that.
While you say not to suggest another system, Fate Core might allow for more distinction between players "specialties," e.g. Lore/Knowledge, in that a Cryptozoologist should be quite different in their niche than a Parapsychologist. While I love FAE, two characters with Clever +3 and similar higher education backgrounds will provide quite a lot of overlap. That doesn't happen so much, say, in the supers genre where Aspects/Power Facts give different permissions.