Well, I do have a story that we might find a way to evolve into an rp. It's a plot for a Metro fanfic that I never got around to writing. It takes place about 18 months after the events of Last Light, for those of you who have played it. This means that the Metro 2034 canon goes out the window, though.
Anyway, story is this: although D6 was successfully defended from the Red Line invasion, the Metro is now more unstable than ever. With the death of General Korbut and the toppling of General Secretary Moskvin, as well as the great loss of manpower and military equipment in the battle of D6, the Red Line has started to crumble. They have already lost three stations - two to the Reich, and one which declared itself independent, only to quickly get rolled over by Hanza. The Reds are not about to roll over and die, though; they are still a force to be reckoned with. Polis has also lost a great deal of power after the Spartan Order was nearly wiped out, and has now been reduced to a militia led by experienced veterans.
Anyway, while this is all going on, there are rumors of a nuclear powerplant outside Moscow, still functioning, and capable of giving power to the entire Metro. A prospect as terrifying as it is wonderful, as power to the whole of Metro would mean light and life for all, but the ones who controlled it would control the Metro. I guess for the RP, the players would be sent out to find the reactor, going both through the Metro and on the surface. They wouldn't be the only ones though, and will have to fight through hordes of mutants, bandits, Nazis, Commies and even Hanza.
It's an idea.