Yac

That's one of them, though by far not the best one. What I find great is that this became sort of an open world for anyone to write in - Glukhovsky gives his blessing and off you go. Of the 9 Metro books I read only 2 were written by the original creator of this world. One of them was for example set in post apocalyptic .. Rome (and Vatican), which was a very unique setting. One I'm just finishing is set in Postapo Poland - though unfortunately it's the weakest one of them all imo, so far at least. I can't wait what for example Scandinavian authors come up with.
Yac.