Metro 2033 First Generation story one A Stroll Through the Park

Metro 2033 first generation will be a a part a of three stories, A Stroll Through the Park is the first one, It's about four teens that run into each other deep underground, they decide to help each to get back to their home station, they decide to go through post-apocalyptic Moscow, they have to survive the radioactive surface and fight off the monstrosities that live on top