(This take place in the future and past and multiple other dimensions...)
After many millennia, humanity dispersed among the stars. They eventually invented far more than they could previously comprehend, and perhaps never truly mastered.
Time travel turned out to be far more incredible than they anticipated, as it was not only truly their own timeline and other timelines they could travel to, but other realms with absurdly different sets of dimensions. Like a super-flat man made of paper eaten by a tornado, they didn't initially last long in the 4th dimension. With intense experimentation and foresight, they eventually could stand on their own for short times with technologically advanced aid.
The ability to create an entire universe was born, and the first few realms grew slowly and eventually stopped expanding. They were empty voids with not even air. But after enough experience and countless casualties, an entire universe with a fractal design grew indefinitely. Another was made, with a finer fractal design. Eventually, they computers were made out of infinitely expanding realms- some of which were themselves universe creating machines. Others were self aware, and a few such realms essentially existed as only emotionally-charged devices. An entire torture chamber for just one soul could be conjured in an instant, a being kept alive only to suffer, and others were pleasure kingdoms filled with amazing experiences and some were gloomy prisons with endless sadness.
Even souls were eventually created; Swarms of nanobots numbering in infinities were sent through perhaps every timeline, into every moment, to capture every portion of a conscious, and each such moment was cloned infinitely, and each clone of each moment was psychically connected by higher realms.
True immortality was attained, as such entities could write themselves into the fabric of the omniverse, and even that was the only thing that stood hardly on par with near omnipotence; Several self-proclaimed gods, among many quieter and wiser creatures, could create impossible things imbued with mutually exclusive properties.
These entities wage war everywhere, but yet are never anywhere.
Like mere squads of submarines in an infinite ocean, even the most powerful and numerous legions, infinite in scope, could never actually attain dominance over all others. But they had victories and defeats... plenty.