What about...
You must win a conquest victory (vassals are enabled?)
You must always (if possible of course) be in Police State, Nationhood, Slavery, State Property, and Theocracy (perhaps beelining these techs?)
You may only build military buildings, production buildings, and Monuments (yes, that will lead to unhappiness and unhealthiness, perhaps you may only build a Coal Plant and not a Hydro Plant or those others?)
The same as above applies to wonders (Iron Works and Pentagon are allowed, but the Pyramids for example isn't, great people may still build their special buildings though)
That probably will be a hard enough game for you...