In CI4 there was Egg City boss whose fragments flew away in a supermassive black hole. This wave has 1.2% chance to replace asteroids wave. The level will be similar to asteroids: City fragments fly in space, you can kill them, you can die after a collision. Nothing special, just an Easter egg.
How would the egg city fragments make their way to that new galaxy though?
Yeah, but they are notoriously unreliable.
Thats why It has only 1.2% chance.