I will describe below a mechanic. I have not implement it yet, so I can still change things. I'm looking for a simple what you think about it (if I should implement it or not or change something, maybe something should be adjusted, etc), even simple "pathetic", "I won't play it", "I love the concept" would be helpful.
Older topics (similar):
http://www.gamedev.net/topic/660026-emperor-and-rebels/
http://www.gamedev.net/topic/670355-loyalty-etc/
Mechanic
You are the Emperor of a space empire. Important part of the game is an internal struggle (so not only fighting aliens), major part of it is rebels mechanic.
There is an abstract "rebel power" which accumulates over time (because people are unhappy, due to food riots, a secret organization wants to overthrow you, imperial officials being disloyal, alien plot to destabilize the empire, etc), it's basically a sum of various factors. When the rebel power reaches a certain thereshold a rebellion event starts (and the rebel power variable resets). There is no distinction who the rebels are, it's a generic rebel forces (entities that are unhappy with you being on the throne) that want to conquer the imperial homeworld.
So, rebellion, once it starts, is a sort of game mode. Until it ends the rebels will spawn forces, attack imperial planets, take over planets politically, etc. If you are unable to crush the rebels (make so there are no rebel controlled planets anywhere in the galaxy) within 50 turns you start losing prestige and eventually will trigger a failure condition (so you can't go for status quo, you have to crush them or lose the throne). Also if at any time the rebels control the imperial homeworld you instantly lose the game.
Details: At the start of the rebellion event 3-5 planets turn rebel (probably the outskirts ones, homeworld and near homeworld planets are immune). Then rebels start spawning rebel forces (each turn, but much more at the first 5-7 turns of the rebellion). Eventually they stop spawning new units (turn 10-20) except for small contingent allowance per controlled planet (sort of production, rebels in fact do not produce anything). They will have an option to politically take over a planet (without a combat and only if the planet loyalty is sufficiently low and is neighbouring another rebel planet), but only during the first 12 turns of the rebellion. Then they fight with you over the control of the planets. If you crush them within 50 turns you are fine, if not you start to get penalties and eventually lose the game (like turn 70-80 of the rebellion). There is no negotiation with rebels :)
Additonal mechanics/questions:
- I wonder about just one variable "rebel power", maybe make it more complex? (but reasonably, I don't want to/have time to make a rebellion simulator :D)