The open rebellions are a neat idea, but I feel like they're implemented a little badly. It seems to me that they're intended to make culture more important, and punish you for not keeping your culture up besides the extremely slow, easy to counter enemy culture creep, which is a good idea on paper, but the way it works in-game I think is not so great.

For one, it's infuriating to have a single planet constantly suffer from open rebellions over and over, I think a planet ought to be unable to have an open rebellion for like 5 or 10 minutes after colonization. It's very silly to me that I can colonize a planet and then almost  immediately have an open rebellion before I even have enough time to set up culture.

I also think that the check for allegiance should somehow be applied before planet bonuses such as ordered society, death world, etc. My reasoning for this is that I find it very annoying that I am being punished for something I have no control over, it might not be feasible or even possible for me to get my allegiance past the maximum just because of planet bonuses.

Basically, what I mean is, let's say we have a Death World, it gives, among other things, -15% allegiance, it's far from the capital, so it has the minimum base allegiance of 35%, reduced by 15% by the death world thing, to 20%. I think that the open rebellion check ought to see the 35%, rather than the 20% after the bonus, since we have no control over what planet bonuses we get. I dunno if this is feasible, but I think it would make open rebellions a lot less infuriating!

Edit: Reading the OP, I see it's only supposed to happen if the planet is affected by enemy culture, but this is most DEFINITELY not the case. If it were this way, I think Open Rebellions would be totally fine even without any 5-10 minute immunity after colonization.

I colonized an distant barren world in different star system colonized by none else but me and I have colonized an asteroid system first before moving onto that barren world.

I had at least first two population upgrade completed to get rid of underdevelopment penalty.

With frigate factory and planeterary shields and planet defense currently in upgrade phase.

Then my fleet left to take over an oceanic world..

Bam Open rebellion occured on that barren world and pasted everything in queue including two ralz heavy constructors which was intended to build two star bases to protect that world. Welp. Didn't see any capitals so I think it wasn't full rebellion but almost there was like 30 or 50 ships.

I sucked it up and moved on and colonized few more worlds before coming back to that barren world with reinforcements for my colonizing fleet.

And then I turned the rebels into space dust for their insolence to rebel against me the great emperor of all that exists and went back to colonizing the rest of this small star system.

edit: I didn't know it was supposed to be effect by enemy culture only, I just thought that the independent planet which I just oppressed to under my rule really wanted their autonomy badly enough to get themselves kicked by me for 2nd time.

*raspy voice* Excellent... there is promise in you yet.

The crazy rebellions in 1.80 were fun to watch, but not so much to play against. The first time I saw them, I said to myself... "Ah, so that's what Rebellion in Rebellion is about". I think I still have a save game where 3 planets rebelled, each with a cap ship, a dozen heavy cruisers and a zerg of other ships. Combined they had more fleet than I did, and I had practically won the game by then. In 1.82 I don't think I've seen any, probably because I don't have any trouble keeping allegiance above 25% [vs. AI anyway].

I'm surprised nobody commented on the econ upturn/downturn or the Gamma Ray Burst. They can have big impact on the game. I guess they are disabled by most playing on ICO (because of that.) In SP you game/cheat the game by saving when the timer for deciding the next random event is about to expire (every 10 mins, IIRC) and if you get hit by something ridiculous (like GRB ray on HW or nearby [because it will then travel to your HW]), reload. GRB in particular is worse than pirates. Perhaps there should be a "Fair" version/subset of these events, e.g. only those that affect everyone.

Even the econ down/up can have a nasty impact in an unbalanced start in MP, even though those two affect everyone. Upturn when rushing someone is basically the end of that because they can pump lotsa ships. Downturn tends to favor the attacker, if he has fleet superiority already.

I just run with them off, and I'm a SP.  Some of them are way too annoying (GRB) and are too game changing for a "simple" random event.