I like Greg Egan's formula for stories of coming up with a "small" change to fundamental physics, and then follow all of the consequences to their logical conclusions to build the world. It's <https://tvtropes.org/pmwiki/pmwiki.php/Mohs/OneBigLie> to a T. And I really like the "Science" pages on his website that explain these worlds, which a bunch of his books have, including this one (where there are 8 long-lived generations of leptons), Orthogonal (where the time dimension is spacelike), and Dichronauts (where one of the space dimensions is timelike).
Greg Egan's Permutation City is an all-time favourite. The combination of simulation, cellular automata, garden of eden states and Dust Theory blew my mind as an adult in the same way that the Matrix did when I was a kid. Very keen to check out this new work!
Thanks for the reminder. Greg Egan is one of the few SF authors where I don’t feel like I’m reading a “tech themed” fantasy story where the sci-fi elements may as well be magic.
