I'm searching for a sci-fi novel I read about 20 years ago; might be important to mention that I read it in french.
As far as I remember, the story is about a man, who doesn't really know where he is or how he got there, alone in a town. There are no other people in the town. Pretty soon, a woman seemingly appears out of nowhere, with no recollection of how she got there.
Of course they fall in love, even if the man initially doesn't find the lady that attractive at first. I remember them to be middle-aged.
After a time, they are tired of their environment and to be alone, so they want to get out and explore. But they can't. Reality seems to end not far from town, all around it.
Pretty much at the end of the book, it is revealed that they are actually in a computer simulation run by aliens who want to study the long-gone human race. They developed technology to extract all of a person's memory and everything they were from a few dna samples. I think I remember the aliens mentionning that the dna samples came from old bone fragments. The 2 simulated humans are offered to continue living in the simulation or just terminate, I believe. I think they chose to continue living in the simulation.
The book cover might have been a human skull along with rats; not very sure about this though.
I've been searching for this book for 10 years now, I'll be eternally grateful if you help me identify it :)