How can I make a civ more warlike?
There are a number of options. Science is tricky, but I am definitely making progress in making my mod be constant warfare all the time.
Things that seem to work:
Give their civ values that emphasize warfare:
[VALUE:PEACE:-50]
[VALUE:MARTIAL_PROWESS:50]
[VALUE:POWER:50]
and the creature a personality that emphasizes violence:
[PERSONALITY:ANGER_PROPENSITY:80:90:100]
[PERSONALITY:HATE_PROPENSITY:80:90:100]
[PERSONALITY:VIOLENT:80:90:100]
[PERSONALITY:CRUELTY:80:90:100]
[PERSONALITY:AMBITION:80:90:100]
[PERSONALITY:VENGEFUL:80:90:100]
[PERSONALITY:TRUST:0:10:20]
[PERSONALITY:TOLERANT:0:10:20]
The personality of the leader plays a big part in how the civ responds to situations. Not much is known about value and personality exact effects but these traits do tend to create a lot of violence and persecution.
If you want them to war against a specific civ, give them opposing values, make them find something UNTHINKABLE that other civs find ACCEPTABLE. KILL_ANIMAL is a good open candidate for baseline DF. This is tricky though if you want the civ to be "chaotic evil", lawful evil civs are much more frequently the aggressors. It is possible that the VENGEFUL personality trait may cause a chaotic civ to retaliate more, though I haven't tested this.
You can also give them religion spheres that oppose the target nation, i.e. LAW against CHAOS, BEAUTY against DEFORMITY, WATER against FIRE. Civs will sometimes go to war over this. The TOLERANT trait may affect this, again not well tested.
Also make sure the civ's creatures are strong and they have access to good metals. Otherwise their aggression will just get them wiped out in worldgen. Giving my civ giants as war minions seems to help.