Bombardment

After a thorough investigation, we have come to the conclusion that … was the site of an ancient genocide. As far as we can determine, the native population of … was on the verge of becoming a space-faring race when a far more advanced race suddenly entered the system, bombarded … from orbit, and left again, leaving the few survivors doomed to extinction.

The command below will trigger the "Bombardment" event in Stellaris:

When this event fires, you can choose between the following option:

• Study the impact sites for details of the weapons used.
  • Add deposit: Ancient Bombardment Craters

Stellaris events fire in chains — one event leads to the next. Here is how Bombardment (colony_mod.6) connects.