Something like this could work IMO. But would need carefully adjusting as when and how bid the bonuses were, Starting at the same "level" as the played could badly    put the AI behind the 8 ball and impossible to catch up.  A extra starting planet or two would be an advantage that would take time to build up,

Interesting concept. Really it could effectively get rid of difficulty levels for the most part. If the ai got penalties or bonuses in relation to the player as the game went on. However, that would potentially make the game insane as an empire with a couple of planets left started cranking out ships every turn. It would require a lot of work to balance this.

This; the game rewards early expansion heavily. If the AI is struggling in the late-game, it's usually because it didn't do as well early on as it appears to have.

Tbh, the thing that will make the AI better late-game isn't any artful tweaking of the difficulty level bonuses; it's making it understand the adjacency system. The player does, and capitalizes on it. The AI doesn't, and so it's late-game planets are massively less productive.

You are right but it is only a part of the full picture.

Because it is also about the ship design. A Player can really exploit it by using sensor ships (cargo ships with only sensors) to get a massive vision and no need for sensors on other ships. And then you can stack up research that reduces the room that ship parts need (60% with research, additionally 10% extra for weapons and armor and if a special event happens a malevolent race can get additional 10%). That means a Player ship can have 3,3 (5 with the event) times more weapons and armor and 2.5 (3.3 with the event) times more of everything else. With a fleet of those ships no AI Fleet can even scratch your ships and they can move 20+ tiles per turn, sometimes killing 5 or more fleets in one turn.

Yes the price of those Ships also increases by the same amount, but that doesn’t matter much, because like you already said, with the stacking of adjacency it is possible to reach insane production numbers (especially on malevolent home planets with the  +10 prod from a malevolent trait, +50 from the Death furnace, than +25% from another trait and then all production gets another 100% Military Bonus from another malevolent trait). And this things also buff each other (the death furnace bonus becomes 62,5 with the 25% trait and then 125 because of the military prod Bonus).

And the adjacency Bonuses can even exploited more, with the "logistic reduce building" and the "ship capacity increase building" and max military adjacency bonus for them you can get more than 50% more space on ships (and your ship parts only need 40% of the regular space, so the bonus is 125% in reality) and you can reduce the logistic needs of the your ships too, resulting in more than twice as large fleets).

If that is not enough than you build a Fleet with Lasers as their only weapons, a Fleet with rockets and one with Kinetic. Because you have so much movement points, the AI cant reach your fleets in one turn while you can decide which of your fleets attacks his fleets (Oh yes and you have endless vision thanks to the sensor ship).

Add this all up and the AI is screwed after the early game.

100% agree

So, in short, our main problem isn't AI bonuses, but the sad fact how its unable to anything meaningful but rushing to all available space without even "analyzing" that he's doing (like colonizing planets inside players ZoI that goes into rebellion in 4 turns). It can't properly scout and have to resort to tricks, it can't specialize, it can't use tiles placement and other related things properly, it can't even properly use techs to buff ships (in my game Altarians had like x3 more research progress than everyone else, but heir ships were total crap). The only thing it can do  is to get as much planets as possible and try to harass player with it's sheer potential from manufacturing (for evil races) or research (for "good" ones). And even that could be countered by spamming ships - looks like AI use your power rating and not your actual ships to decide if you're dangerous or not.

My first reaction when I read this: I seem to remember a certain mod in another game with a 'flexible difficulty' challenge option once. I wonder if we might see something similar here?

Alright, I've come around to agreeing that Handicaps are the easiest way to arrange the AI's production, so let's give this a shot.

Someone come up with ballpark estimates of what the bonus for Genius and Godlike AI's should have at T1, T50, T100 and T200 and we'll work out a decent formula to get there, then we'll see if we can throw it in a mod.

Currently we've got this for Genius:

<Stats>
<EffectType>ProductionPoints</EffectType>
<Scope>Global</Scope>
<Target>
<TargetType>Colony</TargetType>
</Target>
<BonusType>Multiplier</BonusType>
<Value>0.25</Value>
</Stats>

i.e. a permanent 25% boost, compounded by a -25% manufacturing cost multiplier.

And this for Godlike:

<Stats>
<EffectType>ProductionPoints</EffectType>
<Scope>Global</Scope>
<Target>
<TargetType>Colony</TargetType>
</Target>
<BonusType>Multiplier</BonusType>
<Value>3.0</Value>
</Stats>

So a 300% boost, compounded by a -50% manufacturing cost (i.e. they can produce 8x as much as a human) from the start, all the way through the game.

We'd have to find some way for the AI to itteratively adapt its multiplier each turn. It would basically be something like

<Stats>
<EffectType>ProductionPoints</EffectType>
<Scope>Global</Scope>
<Target>
<TargetType>Colony</TargetType>
</Target>
<BonusType>Multiplier</BonusType>
<Value>0.01</Value>
</Stats>

added on each turn.

I don't really know how we make it adapt that yet, but it could be tied to techs - we could make an AI version of the tech tree, where each tech increased its manufacturing multiplier or added a flat rate.

Anyone got any ideas for a more elegant solution?