A question about diplomacy

I've never been able to get treaties to appear in the game even at launch. Except for Alliance, that is.

You have to research them. They're low-mid to high-mid tech. As you research them you choose different branches. But idk what the different alliances do. Like, I don't see any difference between  a technological alliance and a military alliance. 

As far as I can remember, you also need to have good relations with them as well. The treaties give you a percentage of your partner 's research, culture or production if I'm right.

Ok, how about the alliances? I can't seem to find any info on that ;~; Maybe a modder knows? 

An alliance is if anyone attacks you your allies join your side.

Have you ever seen it actually work?  I have tried but no joy

Works 100% of the time for me. but it's essentially a mutual DEFENSE pact. Anyone attacked is defended, anyone that declares a war is on their own.

If I'm reading the XML correctly, what really happens is that all of your colonies and all of their colonies get a 25% bonus to the approrpriate output (research, gross income, or culture generation) that stacks additively with the bonuses from the improvements which already exist on the planet. The treaty is essentially a free market/lab/cultural center (dependent upon treaty type) on each colony you have; the economy of the faction you've partnered with has nothing at all to do with the benefits you receive, as far as I can tell from the XML. As such, unless I've misread the file, the treaties are really rather marginal in effect.

The treaties are defined in TreatyDefs.XML if you're inclined to look for yourself, by the way.

It should be possible to also sign packs where nations agree to go to war alongside the aggressor. A pure defensive pact is only so useful.

I have never seen alliances work for me tho @@ Like, I was declared war on. My 'allies' were neutral to the enemy. A dozen turns later they're allied to the ones who declared war on me >< 

Basically this. You also need to have the tech for them, and for the econoic/science/culture treaties you need to have a relations value of at least 4 for them to appear on the list.

As to alliances... as far as I can tell they have no direct in-game effect. You just collect them for diplo victory. I think they're supposed to cause AIs to get hostile to enemies of their allies pretty quickly - the xml seems to indicate it - but I've never actually seen any such thing happen in game.

My allies do eventually DoW my enemies, but usually at the point that I've crushed them militarily, so they're probably just triggering the 'you are ripe for conquest' modifier. Certainly, lots of other empires which aren't allied to me seem to join in around the same time.

Ever tried a military alliance? That might be what it's for. I've never used it, though, and it doesn't appear in treatydefs. Pretty wierd.