Leaving an alliance 'just by pressing' a button seems to be the problem here. There should be some consequences (though I think removing already researched tech in retrospect is not a good idea IMHO) to it. Or maybe there should be some upfront cost for beeing able to leave in the first place. Something like paying influence to break off. The value required to do so then scales depending on how close the alliance is to game victory.

It is quite an issue that may be hard to fix. I feel what they could do is add somesort of penalty, where leaving an alliance makes you unable to win by yourself for about 50-75 turns or so. That sounds like a ridiculous high number of turns, but that'd be enough for anyone to react and deal with the person that's supposed to win and would make that person question if leaving the alliance is worth it.

Alternatively, when you've reached the set goal to win by yourself in an alliance (such as having researched the last 4 techs) you shouldn't be eligible for that win condition anymore unless you're in an alliance again. That ofcourse requires the former as otherwise you could just leave when close at reaching the last tech anyway.

The latter might be harsh, but I think both are fair, you can probably tune them to be less forgiving. It atleast adds an importance to creating/joining and leaving an Alliance, so you have to think twice when you do either or set yourself up for a rough ride afterwards. If you plan to leave, you gotta leave early or plan way ahead which gives the other factions time to attempt stopping you from "using" them if you're a threat.

This might not work too well with AI who already got hard time responding to a player being close to victory, but would work well for players. You could however do it so when you leave an alliance you lose a big diplomatic status with the previous AI allies so they're more likely to declare war on you for it, since joining and leaving an alliance shouldn't be a small thing you do on a whim, imo.

Agreed. I think alliance victory should either be reworked entirely or removed from the game altogether. Like you said riding the coat tails of an alliance is a big issue and we've been discussing stuff about victory conditions in general in another thread. The flipside abuse of the instant change in victory conditions when leaving / entering an alliance is that empires who have never worked together before in the game can also ally together if both sides notice they have enough systems, wonders, victory techs, Dust, or capitals, and win instantly in one turn. There is no counter to this.

I've been complaining about these issues for so long that I decided to turn them into few possible ideas.

removing alliance victory would turn the late game in multiplayer into a backstab party.
why not if one member would win, everyone of the alliance win, or if you have a soloi win condition, but not an alliance victory condition, you can't leave the alliance

In addition, a "buyout" penalty for leaving an alliance would not be sufficient; I was swimming in dust and influence at this point and could easily pay those kind of costs.

Yeah, it's practically impossible to win a science or wonder victory in an alliance, because the AI doesn't go for those. Dropping out is the only way. 

Acutally, I just looked at my Empire Chronicles and I did win a wonder victory as part of an alliance. I had forgotten that I built 6 copies of the wonder (that's allowed). But you can't research the victory techs extra times.

Can you gift the necessary Endless Tech to an ally? I have never tried allianced victories yet.

I've actually had the Sophon AI research 2 of the Endless tech in my playthrough, but they were fairly far ahead in science compared to everyone else, right behind me, and our alliance had more members.

I think it's fair to assume that what the factions are best at that's the kind of victory they'll go for, so I can see Sophon and Vaulters AI actually getting Endless tech with given time, but doubtful if the other AI factions would since they're not science focused. Wonder victory is one I've not seen the AI go for, so assuming they don't is likely for now.

Numinumi wrote:

I've actually had the Sophon AI research 2 of the Endless tech in my playthrough, but they were fairly far ahead in science compared to everyone else, right behind me, and our alliance had more members.

I think it's fair to assume that what the factions are best at that's the kind of victory they'll go for, so I can see Sophon and Vaulters AI actually getting Endless tech with given time, but doubtful if the other AI factions would since they're not science focused. Wonder victory is one I've not seen the AI go for, so assuming they don't is likely for now.

I think I have seen my Unfallen ally building a wonder (by which time I had already completed 5).  I am not sure how that translates in difficulties above normal.

Looking for "small solutions" this is what I would think about:

-Remove alliance victory from current system.

-Add the option of forming a "permanent alliance" as an upgrade to the standard alliance (just like a trade contract offer).

-Pop Up warns you (the orange full screen warning dialogue that is already in the game): Permanent alliances will last forever and cannot be undone, are you sure you want to offer/accept this?

-Add allied victory back to "permanent alliances".

Hi,

I'm a new player (3 games at the moment, one lost, one won in alliance by conquest and third one won leaving an alliance just before research the forth victory tech).

Was this issue ever addressed in any way? 

Paying insane amount of Influence to leave a long date alliance seems the correct solution for me.