Athena Minerva
One tiny change...
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The Laws of Athena Minerva
Advanced technology gets introduced from malevolent forces from a parallel world roughly a thousand years earlier than it would be developed on this world. We barely survive
Cosmology
At first the only difference is a mutation which allows males to deliver a great deal of "life energy" to females during the mating process. And disease antibodies. This small change causes sexual promiscuity to be a healthy activity, which dramatically changes one facet of human societies while the remainder of history stays pretty much unchanged.
Principal Geography & Features
The geography of the World of Athena Minerva is exactly like our Planet Earth Prime on the Prime Material Plane.
Initial Active Setting
Most stories involve only a few characters in a single town or on a single spaceship.