It stinks and they don't like it
Common64.4%ObjectiveOptional
Trigger an alien attack by pollution.
Trigger a biter attack with pollution. Just run your factory - the pollution cloud spreads to nearby nests and eventually provokes them into attacking. On default settings it happens on its own within the first hour or two; to hurry it, cram pollution-heavy machines (boilers, furnaces, drills) near a biter nest.