On: Factorio is coming to Nintendo Switch

[323]

The monsters only attack after their land is polluted:

> Pollution attracts biters to the Player's factory. Biters who find themselves in a polluted area will attempt to reach the source of pollution and destroy it.

So you can say they are the ones in self-defense.

[nmeofthestate → 323]

Only because pollution alerts them to your presence. Walk near enough to them and they'll attack you, pollution or not.

[cesarb → nmeofthestate]

> Walk near enough to them and they'll attack you

There's also the expansion groups, which will periodically move around to create new nests. Even if you don't walk at all, you will be found and attacked sooner or later.