I like it. It's a little bit like Anomaly Warzone (reverse TD) with way more strategy. I also like the night environment *but* it may be a little bit too dark, don't you think? Is it a game mechanic? Can you get a special weapon that let you see more of the battlefield or is it a pure visual effect? In the latter case, a more "gradient" effect (i.e. lights have a bigger radius of effect) would be better.
Anyway, keep up the good work!