Well, here's Version 1.1 of AI_Analysis.txt, which now covers the Politics and Settings files in addition to its specialty, the Anger files. Have a happy the-days-are-now-getting-longer-in-the-northern-hemisphere celebration of your choice.
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Well, since nobody else has done it I decided I needed to go into the various AI behavior files and describe how the various computer players now differ.
Most of the analysis below is of the AI_Anger files, and is relative to Default_AI_Anger.txt. I think there are some variables that aren't shown there, as I have caused a race to go to war with me just by flying a scout through their space before I had a treaty with them (even though that race had "Per No Treaty Ship" set to 0). Also, having a system claimed by both you and them seems to cause anger, but that isn't shown either.
The things that show up in the files that make a default AI race angry (in order of how angry it makes them) are: being Mega Evil, demanding their surrender, declaring war, beating them in combat, refusing/breaking treaties, asking for gifts/tributes, surrendering (?), doing intelligence projects against them, refusing trades/gifts/tributes/demands, demanding that they remove ships/colonies, demanding that they leave planets, asking them to end wars or break treaties with others, losing to them in combat (!), and having planets they want. A combat ending in stalemate does not make them angrier, even though winning and losing both do, so if you want peace, go for the stalemate. The things that make them happy are: granting independence to colonies (?), accepting demands, accepting treaties, and giving gifts/tributes.
In addition to the AI_Anger files, there are also some interesting settings in the AI_Settings and AI_Politics files. Outside of the two Xenophobic races, the AI_Politics files are more or less identical, so I'll discuss them mostly in general terms. Note: when I say "stronger" or "weaker", I am referring to the Score as it is available from a button on the Diplomacy screen.
When an AI is considering whether or not they will accept/propose/break a treaty, they consider: how happy they are with the other player, how big a treaty it is (they practically have to be Brotherly to accept a Partnership, but they'll accept a Trade Alliance at a much lower level), how many wars they're currently in, and whether the other player is significantly stronger or weaker than them (they are much more likely to accept treaties from those with 150% their score, and much less likely to accept treaties from those at half their score). On top of all that, they are slightly more likely to accept/propose treaties in the first 50 turns.
If you have 150% of a computer player's score, you can get them to say they'll obey most of your requests/demands--but as others have noted, telling them to get their ships out of a system (for example) doesn't usually work even if they say they're leaving. If you have six times their score, you can make them a Protectorate; if you have eight times their score, you can Subjugate them; if you have ten times their score and are not allied with them, you can get them to Surrender.
The two fields that vary the most between one AI_Setting file and another are "Percentage of Allied Planets to consider as Attack Locations for Anger" and "Percentage of Enemy Planets to consider as Attack Locations for Anger". Those are just really long to type, so from here on out I refer to a planet that is "considered as an Attack Location for Anger" as a `coveted' planet. Don't ask me exactly what it means for an AI to covet a planet; you now know as much as I do about it. Presumably the AIs get angrier with you the more of your planets they covet.
If a race is Forgiving, they get less angry 4 steps per turn, anger from combat is slightly lower than normal, they wait 12 turns from the Last war before even considering a friendly treaty, and they do not covet enemy planets.
If a race is Neutral, they get less angry 3 steps per turn, they wait 15 turns from the Last war before even considering a friendly treaty, and they covet 10% of enemy planets.
If a race is Angry, they get less angry 2 steps per turn, no-treaty ships make them angry, anger from combat is about 50% higher, anger from refusing treaties is doubled, they wait 20 turns from the Last war before even considering a friendly treaty, and they covet 20% of enemy planets unless otherwise stated.
However, if an Angry race is also Xenophobic, they only covet 10% of enemy planets (I guess it's lower 'cause they think the planets have been contaminated by those unholy aliens?), no-treaty ships make them furious, and anger from combat is doubled. Not only do Xenophobic races hate being communicated with in almost any way, but they need to be happier with you to accept treaties, they are one-third as likely to propose treaties as the other races, you need to have FIFTY TIMES their score before they will surrender, and they are 50% to 300% harder to intimidate with all other threats and demands.
Abbidon: Neutral race. Covets 25% of allied planets.
Amonkrie: Angry xenophobic race. Covets 20% of allied planets.
Cryslonite: Angry race. Covets 30% of allied planets.
CueCappa: Forgiving race. Covets 10% of allied planets.
Drushocka: Neutral race. Covets 30% of allied planets.
Eee: Forgiving race. Covets NO allied planets.
Fazrah: Angry race. Covets 30% of allied planets.
Jraenar: Angry race. Covets 30% of allied planets.
Krill: Angry race. Covets 40% of allied planets.
Norak: Neutral race. Covets 20% of allied planets.
Phong: Forgiving race. Covets NO allied planets.
Piundon: Angry race. Covets 30% of allied planets.
Praetorian: Forgiving race. Covets NO allied planets.
Sallega: Neutral race. Covets 20% of allied planets.
Sergetti: Angry xenophobic race. Covets 20% of allied planets.
Terran: Neutral race. Covets 25% of allied planets.
Toltayan: Forgiving race. Covets NO allied planets.
UkraTal: Forgiving race. Covets 10% of allied planets.
XiChung: Angry race. Covets 40% of allied and enemy planets.
Xiati: Angry race. Covets 50% of allied planets and 10% of enemy planets.