40d:Immigration

Immigration can occur during any season.

The total number of dwarves in your fort is limited to approximately 200. (configurable in init.txt, up to a maximum of 1000, and a minimum of 8) It will take several years to reach this number, assuming you want to reach it at all. Once you reach the immigration limit, normal immigration will cease.

How immigration is calculated

Immigration figures are based on your fortress's total "Created Wealth" (visible on the Status ([z]) screen once you get a bookkeeper). All objects with any value (including mined-out areas, bridges, and just about every kind of created good) will be included in the total. Artifacts are one of the largest influences of fortress wealth. Artifacts made of precious resources and heavily decorated can potentially double fortress wealth early in the game.

This created wealth will be witnessed and reported back to the world by the yearly dwarven caravan. If the caravan dies before making it back to the dwarven capital (if they fail to make it off your map), then the previous caravan's report is used to determine this year's figures.

Immigration is usually limited to about 20 dwarves per wave, plus pets.

How to influence the types of dwarves that immigrate

You can't, really, although it is believed that the immigrants' skills/careers might be influenced by the type and number of workshops available. Noble immigration, however, is dependent on meeting specific conditions. See nobles for more information.

Soldiers will only arrive if you have made their type of weapon; if you make one battle axe, you will only get axedwarves. If you make a crossbow and a war hammer, you will get crossbowdwarves and hammerdwarves. This is not affected by weapons brought to your fort; getting immigrant carpenters won't let you get immigrant axedwarves. It is not known if the number of weapons created matters.

What are the drawbacks to immigration?

Most of the time, immigration is a Good Thing, and the more, the merrier. More dwarves means more work gets done (especially hauling, since immigrants are basically peasants), more dwarves can be given "luxury" tasks like defending the fortress or making dyed cloth, and some nobles require a certain number of dwarves before they arrive. (Notably, the incredibly useful Manager requires at least twenty dwarves.)

However, more dwarves also means more CPU cycles eaten up, especially if your fortress is already taxing on your computer.

Of course, additional dwarves also require additional bedrooms, workshops, and booze before they can be properly productive, and some players prefer to increase their population slowly to allow them to add the extra infrastructure at a more sedate pace.

How can I curb immigration?

If your dwarves are very industrious, you can expect to receive ten or more migrants in the first immigration wave, which often occurs in the autumn of your first year. The easiest method to handle immigration is to alter the population cap in init.txt. You can first set it low and raise it as you see fit. Note that you may consider this to be cheating, and it also requires exiting the game each time you want more immigrants.

You can also make sure your fort does not produce or build much. Of course, this is not an especially interesting way to play the game. Since artifacts often account for most of your fortress' wealth, killing dwarves that enter strange moods may be a better option. This can often be accomplished by making sure all your workshops are in enclosed rooms, then locking the door on them until they go insane, then starve to death. This has a drawback in that dwarves that do manage to produce an artifact often gain a desirable legendary skill.

You can also kill the immigrants themselves, deliberately or otherwise. Very large numbers of deaths at a fortress, from any cause, (exact number unknown) can cause all immigration (except nobles) to cease for a while: your fortress has gained a reputation as a deathtrap!