Many types of fortress scenarios a user might want to play (penal colony, military outpost, etc)
should affect immigration, but there's no way to influence migrants. There are some suggestions for being able to tell the liaison what sorts of immigrants you want, the ability to reject migrants, and so on, but there'll be scenarios those things probably won't cover, not to mention that for certain scenarios it would break immersion. My suggestion is that there be "scenario profile" files, one of which can be selected from in the embark screen, and after embarked can't be changed.
Of course, to fully play out many scenarios you'd also need to modify how caravans act. That's the second section.
So, migration stuff that would be controllable by a scenario profile:
- Maximum and minimum number of migrants per season. For instance, the number of migrants to a penal colony is going to be pretty constant no matter what's happening at the fortress.
- Change the max/min number over time. For instance, if you want to play a "dwarf-kind's last stand against the zombie-hordes" scenario, the first few seasons you'd get a whole bunch of migrants, the next few the number would start decreasing, the next few would only get a trickle, and then none after that.
- Control how much (and in which direction) various things about the fortress affect migrant numbers. For instance, deaths should have no effect on migration to a penal colony, and should increase "migration" to a military outpost (the military replacing lost soldiers).
- Increase/decrease the chance of various professions and skills. If you're going to do a military outpost, everyone should be from some sort of military profession, and they should also all have at least a little of the student skill to help them learn from combat demonstrations.
- Control/modify the attributes of migrants. For instance, soldiers sent to a military outpost shouldn't be weak of flimsy.
- Similarly, control/modify the personality traits of the migrants. Migrants going to a military outpost should be less vulnerable to stress than the average dwarf, while migrants to a penal colony would be more likely to have unpleasant personality traits.
- Control the male/female ratio of incoming migrants.
- Control how many (if any) married couples come to the fortress. And if any come at all, control how likely it is that they'll bring along children or babies.
- Similarly, control how likely it is that migrants will bring pets.
- The ability to disable any in-game immigration control. A military outpost or penal colony isn't going to get any say over who the migrants are.
Caravan stuff that can be controlled by a scenario profile:
- Control which civilizations caravans come from, and during which seasons. A "last-stand against the zombie-hordes" fortress isn't going to get any caravans from anybody, while a military outpost will get a caravan every season, but only from the parent dwarven civilization.
- Just for flavor and full-immersion, the ability to change what the traders and liaisons/diplomats say to your mayor/trader.
- A list of items certain caravans will provide for free. The caravans going to a military outpost will provide a lot of stuff for free, since it's the military providing provisions for their soldiers. For some items the amount per caravan would be constant, while for other items the amount would scale with the population of the fortress.
- Inflate or deflate how much the caravans charge for goods. In one scenario the fortress might be partially subsidized by the government, so the caravan only charges half of normal. In another scenario, you might have a fortress were merchants would price gouge, so the prices would be increased.
- Control over what the liaisons/diplomats do and don't request from the fortress, and how much over the normal they'll pay for the items. For a mining fortress they'll only want metal bars and rough gems, but they'll pay a lot more than normal for them. Similarly, for a hunting lodge, they'll only want leather and meat.
- Ability to prevent the fortress from exporting/selling certain things. For instance, the caravan to a mining fortress isn't going to want to buy finished goods made from metal, or cut gems.
- Ability to prevent the fortress from importing certain things. A mining fortress isn't going to be able to import any raw ores.
- Change number of guards accompanying a caravan. A military outpost would expect to see a lot of ambushes and sieges, so they'd have a more guards than normal.
- Increase the caravan's weight capacity over what's needed to carry goods in, scaled by the fortress population. If the fortress is going to be selling lots of heavy metal bars the caravan will have to be able to carry them.
