Dealing with Erratic neighbors and over-expansion

[Zalson]

So I've just lost 3 straight games where I've had an erratic neighbor that I've expanded into early. No DoW actions but just taking space that's rightfully theirs without the backup.

Any tips on dealing with Erratic neighbors? In the last game as the Psilon, I had erratic Meklar and erractic Alkari where their cheese alliance won the game on 2394 or something.

[RFS-81]

I don't think this is really related to them being erratic. What makes erratic AIs special is that they have a small chance to randomly declare war on someone every turn, and that's not what's giving you trouble. AIs will attack someone when they're boxed in, even "pacifistic" ones. It's like a law of nature. Once the borders solidify, the classic MOO1 undeclared border wars happen, and buttering up the AIs with diplomacy will not protect you, but it does prevent them from going into total war mode. You can sign a NAP which will give you an advance warning when they go after you, and makes it slightly more likely that they pick another target, if available. Signing an alliance makes it vastly more likely (again: only if another target is available), but that's going to take a long time. Also, don't sign the NAP too early because it removes your ability to blockade unclaimed planets!

Otherwise, see if you can build something to counter whatever the enemy is fielding and do back up your claim.

My general rules for erratic AIs are not to offer large trade deals (unless you're the Humans). Small trade deals to improve relations are still good. Avoid trading them techs that you don't want used against you. That's actually a good rule for all AIs

I wish I knew what to do about alliance cheese (which isn't specific to erratic AIs either). I've lost to this in every Imperium I attempted. Keep checking reports to know who's allied and at war with whom. If you can, have good relations with your neighbors so you can convince them to break alliances. Rapid expansion in the early game helps too, of course.

[haphazard1]

I agree with RFS-81 that your problems are most likely not specifically because of erratic. The AIs hate having their borders pushed and will push back, especially if they have no other direction to expand. They are also merciless about attacking anyone weaker than themselves, which on impossible means you in the early game.

You have to find the production somehow to put some kind of force in place to discourage them. Stomp one or two of their initial probe attacks and they may respect your claim to a system. If they commit landing forces then you are probably stuck with a hot war or giving up the system.

[Zalson]

I think my issue is that I'm reaching too far. I'll try standing up planets instead of REXing to 5 different planets at once.

[haphazard1]

Standing up three worlds and keeping them is better than reaching for five and ending up only getting two. But it is good to make the AI work for the planets it takes, and at least slow down their colonization and development for a while if you can. And sometimes for no obvious reason they just don't grab a world, and you can secure it after all. Not often, but I have seen it happen.

I have difficulty with this phase of the game myself. Stretching too far and getting an invasion force sent at me, sometimes when I have already committed sending colonists of my own so the AI ends up treating it as an invasion and I get a hot war anyway. It is a tough balancing act.

[RFS-81]

The reason why they're not grabbing some worlds are most likely dice rolls. The AIs are really not sophisticated. If my memory and the OSG are right, it goes something like this:
1) The AI decides randomly if it wants to expand this turn. (Agressive and Expansionist AIs are especially eager.)
2) The AI sees that there are no planets it can settle.
3) The AI randomly selects a neighbour to attack (weighted by treaties).
4) The AI picks out the planet it considers juiciest.

With all the randomness, it often pays off to gamble on a world you're not sure you can hold.

[haphazard1]

Interesting info, RFS-81. Still, you can gamble but if that algorithm is correct then the AI will come for you eventually. And the fewer alternatives it has, the more likely it is to come after you. At best you are buying some time, so you better be able to stand the planet in question up with some kind of defense pretty quickly.