Sieges are the most troublesome invasion that my colony faces. The mortars keep setting fires and destroying walls, sending colonists outside to repair, who then get injured by mortar fire. It requires a great deal of micromanaging to minimize the damages.
Attacking the siege is dangerous; without the aid of my defenses, all I have is colonists taking fire and frequently dying or losing limbs. Each siege can be very costly.
My question is, what triggers an event to be a siege rather than a standard attack? Is it a wealth threshold, is it the way you have built your colony, research level, or is it completely random?
From my own observations, they seem to only happen once I'm settled in, which suggests wealth – but I've also built up my defenses and walls at this point.
Best Answer
In Rimworld a siege is considered an "event". Events are random, meaning we have no idea what triggers them.
I, like you, have only experienced sieges once I am well into my colony. There is no real way to tell what/when triggers them unless you were to dig into the code and factor in things like difficulty and storyteller.