I first envisioned this game as a city building game somewhat like Settlers of Catan. However, the key difference was that in addition to building cities and roads, you could also stage an armed assault on an opponent's city. The armed assault would procedurally generate an FPS level based on the terrain of where the city was placed, and you could either win or lose the assault, which would decide who had possession of the city in the end. This would all be based on the economy (militaries are expensive, after all). You would also have ways to pay for increased defenses in your city.
There is a lot missing right now. Currently two players can alternate placing cities, and can select each other's cities to attack. This will launch into the fps mode, which you win by killing all the enemies. The enemies are currently statues that pose you no real threat, but suffice to say with some more time to implement AI, they would more than happy to destroy you! The first player to get to 10 cities wins.