Another idea running through my mind, partly drawn from ‘The War After Roswell’.
Let’s say that it is 2100. Humanity has expanded into space and there are settlements across the solar system. Politically, there is the West (an American-led alliance, basically an expanded NATO) and the Asian Alliance (a Chinese-led alliance.) Both states are quasi-fascistic, although they justify it differently. The West developed harsh security measures for dealing with terrorism and have never really repealed them; the Chinese form of communism evolved to the point where it could allow free enterprise, but not so much political freedom.
The influx of resources from space has had a major effect on the world’s geopolitics. The Middle East is no longer important as oil is no longer a pressing issue. Africa is a maelstrom of competing political units, without any major intervention from the outside world. Generally, the major powers will launch punitive strikes against terrorism, piracy and so on, but no attempt at regime change. Much modern industry has been moved into space, where it doesn’t pollute the world. There is also a major military presence in space and a number of nasty skirmishes between the two major powers, along with rock wars, black colonies and so on in the asteroid belt. Pundits have been predicting a major war for years.
Then a deep-space mission encounters something unexpected; an alien spacecraft at the edge of the solar system. The ship appears to be derelict, but offers the promise of advanced technology to send the human race to the stars. Whoever owns the ship will almost certainly dominate the next hundred years.
And so the war breaks out…