After learning a bit about The Last Federation, I ended up being inspired. Here's the pitch.

Participants would be taking the role of various nations on an Earth-like world with a modern/near-future tech base. The RP begins with an alien vessel jumping into orbit and making contact; from there, players would have to manage their relations with the aliens and each other as they try to obtain technology and support from the aliens. Obviously the aliens have an agenda of their own, so it'll be up to everyone to decide just how far they trust them and what they're willing to do in return for the aliens' support.

The focus would be more heavy on diplomatic, social, and intelligence operations than full-scare warfare, although that's not to say the latter couldn't happen.