Exactly what the header says, a postapocalyptic sci-fi story, but I’ll clarify the question:
\-There are mutant creatures, and some of those mutants are sentient.
\-There are guns, lots of guns.
\-There are sci-fi elements (other than the mutants, of course): psychic powers, robots, lasers… If it has all three, all the better.
\-The Thing That Ended The World happened a long time ago, enough that no living person was born before it.
I know there are a lot of games and RPGs like this, but I’m talking about books.
by zoddoid