uat2d
ಠ_ಠ
Ryukyu isn't that insanely difficult: you can be left alone for the most part, the AI sucks at naval invasions sending only a couple of troops every time and you're safe from the Europeans for a long time.
Oyo, on the other hand, that's impossible, you're always annexed by Hausa instantly.
Trebizond must be a close contestant, if nothing distract the Timurids from the start, you're toast.
Heretic_Cata, it's what Quintillus said, you need those government buildings in the capital for spy protection. Other than that, for the most part, you just need money, revolt risk or stability costs won't matter that much on the long run, you're better off focusing on making money as that will allow you to do everything else (including keeping stability up and revolt risks down).
Spoiler :

Oyo, on the other hand, that's impossible, you're always annexed by Hausa instantly.
Trebizond must be a close contestant, if nothing distract the Timurids from the start, you're toast.
Heretic_Cata, it's what Quintillus said, you need those government buildings in the capital for spy protection. Other than that, for the most part, you just need money, revolt risk or stability costs won't matter that much on the long run, you're better off focusing on making money as that will allow you to do everything else (including keeping stability up and revolt risks down).