And do not forget the races in the Space Empires series.
SE3 had the single greatest random event I ever saw in a 4X. Planets have happiness. Conquering a planet sinks its happiness to ~30%. You must laboriously build system-wide joy facilities, set that planet's tax rate low, and garrison it with a surviving damaged troop, to coax its happiness up.
- If planet happiness falls, it riots. A rioting planet produces 0.
- If a planet is in riot for many turns ... it secedes from your empire and becomes a new AI, which promptly declares war on you . See Scotland vs. FUK (F = former) later this week
In dozens of SE3 games, I saw this happen only once, ever!! I spent many games after that trying to recreate it! AFAIK, SE4 and SE5 eliminated that possibility, which was tragic.
I would pay money for a 4X that allows this to happen!!
- Corollary: The "Rebellion Start" scenario. There was a sim of 100 AIs against each other. It was long and bloody. One AI ruthlessly exploited its conquered colonies, until finally ... a colony rebelled and seceded from all AIs, and became ... You. On turn 0. Welcome to the game. You are surrounded by hostile AIs. You have just declared war on one of them. It's coming to take you back. Fight.
I'd pay money to play that, too. It's like Robotron dropping into a Mikey level with brains and cruise missiles!