The Tyrants of Ahton-ak

Imagine that the oldest civilisation in the universe, at the height of its power, is
forced to compromise with its finiteness because the scientific community made the
mistake of not considering the cosmos to be still too compressed. Hundreds of thousands
of years that could have been spent in peace and progress were instead wasted in
senseless wars, the desire for immortality and collective madness. The escape from the
home planet of the survivors from this insanity to Ahton-ak, a world in another
dimension, to get away from it all, where the normal laws of physics did not exist,
might not have been enough to save them from the end of time anyway, but it would
certainly have saved them from the "momentary" expulsion of matter from their sun as it
transitioned from red giant to white dwarf. Things would not have been any better on
Ahton-ak, indeed the ancient civilisation brought with it the "disease" of omnipotence,
eventually three tyrants took control, while no one repopulated the original planet
Ahton. Tens and tens of thousands of years later, in the original dimension, on another
planet, the same sun, the planetary nebula Gharis had long since warmed Loth-dru, the
dying planet of the protagonists of the story, who led their world to the discovery of
a 'forbidden planet', barely mentioned in certain religious texts and legends, modified
by human interpretation over time...