"Are you telling me that we are nothing more than... guinea pigs?"
"I... don't know what that is. A creature of some sort, I assume. The point is, they used planets like yours, planets they saw as lesser and worthless, as testing grounds. They designed the mutagen to force the evolution and gene alteration of different species, all for their own goal.
They would mutate and change in billions upon trillions of different ways. From the slightest changes that could result in the same end result, to wild differences that could produce something fantastic... or something monstrous.
The System, the Artificial Intelligence integrated into the soul of every being effected by the mutagen, would track their progress and changes, then report it all back to the Apotheosis group.
They sent out millions to different planets, and simply waited for the results. Their tests were completed with different variables, and they didn't have to do anything.
