If you grew up playing Apogee's raptor, like all the cool kids did, then you will love Not Your War. Well, I dont know if you'll love it because it is not viewed through the eyes of nostalgia and most of the mechanics, graphics, sound and "backstory" are completely different.
But the concept is the same: you play as some kind of plane-thingy, the camera moves up, enemies move down, your bullets move into them, everbody's happy. Except the enemie's mommys.
What sets this game ahead of Raptor though is the great music, the griddy and awesome graphics and the fact that it has some sort of backstory, told in stills with text.
Im sold on it. The only thing I still find kind of weird is the upgrade system. You just get to choose upgrades at arbitrary moments in the game. Don't know why or how.
Anyways, check it out, if you want to kill about an hour.