I have a sneaking hunch this may already be in there, but if not - a flag to make some units available only if you are in a certain government.

Like?

Well, for starters, a Fascist for Fascist Governments only, like in CTP. Also, actual spy units for various governments with different abilities - Like a Revolutionary for Communism - much better chance of success with propaganda vs Monarchy/Despotism - need extra coding for this, I suppose. You can implement some things like this now by using civ attributes, but by government type would also be nice.

I dont like the idea personally, as spying is alreadt satisfactory the way the game is, not to mention a "faciust" unit is kinda stupid... CTP is not a game i would trake hints for greatness from anyway...

LOL - CTP wasn't really that great in alot of ways - truly bad AI, silly future advances, etc. but there were a few good ideas in it, plus I really did like the graphics - I remember someone here or at Apolyton once called it a shiny broken toy - and yes in many ways it was broken, but my, it sure was shiny. UU by governments was implemented in civ2, also (Fanatics), so don't knock it as another CTP abortion.

I think its a pretty good idea. I liked the fanatics and its limited availability in CivII