The Bet Genre
It might be easier to figure out the genre of this thing by first figuring out what genre it isn't. Do we have particularly memorable characters or deeply felt interpersonal relationships? No, not really. Amazing adventures or romance? Nope, not that either. How about any humor or fantasy or horror? Yeah, not so much.
So what exactly do we have here? We have two nondescript people in a nondescript place whose main function is to try to get to the bottom of an argument about freedom, or community, or what it means to be human, or how much a life is worth, or… something. The short story explores all sorts of philosophical conundrums—and manages to do it in just forty economical paragraphs.