Metro: Last Light is the sequel to the post-apocalyptic Russia game based on the Novel Metro 2033! This story has influenced me greatly with the ideas it has on evolution. I highly suggest reading the book Metro 2033, but I also suggest playing the game! While the gameplay of the first Metro 2033 wasn't perfect, but it did do a very good job of immersing you into the story. It had a very interesting currency system.
Since you are inside of a series of tunnels underneath Russia, ammo is hard to come by. The people living in this shattered world have to make their own ammunition called "Dirty Rounds". But when they come across pre-apocalypse ammunition from the Russian army, they're used as currency! This trailer makes it easy to see there is turmoil still within the human effort.
Is it all humans against humans though? Well, let's take a look at the Metro 2033 trailer and you can find out for yourself!