Seems bugged for me. For me level 2 kept looping. Every time I'd beat it, it would just restart it. No enemies to deal with (not sure if they were meant to be in levels 1 and 2 as they seemed more 'learn the controls' levels but thought I'd mention it since level 2 layout seemed like it was meant that you would duck into the alcoves to avoid enemies).
One idea to improve is adding an ambiance of gunfire/war sounds.
Otherwise, seems like a pretty solid game concept and matches it's source inspiration very well :)