Great game, yet flawed.
The music and cinematics were absolutely superb, love them.
Buuuutt....Once you upgrade something to max, it suddenly becomes a MUCH MUCH worse gun than what you started with, yet I actually managed to get the perfect strategy for the game. Max shotgun out to JUST before it up(down)grades(check the prices on hologram before it 'maxes' and then don't go higher on yourself). Then, simply shoot shotgun forever, it's the most powerful gun out of them all and when upgraded, it'll instantly kill most enemies and charge insanely fast compared to the rate of respawning.
A couple things wrong with this as well, since you never actually have to upgrade your trooper if you upgrade only a certain gun and don't change your guns into the other things, you'll never get hit. Thus, I never did find out what upgrading the other abilities does(Except the fact that you're FORCED to upgrade jump at least some to make it past >_>). Nor did I ever find out what upgrading my grenades does, since there was absolutely no need. Also, if you get too far ahead and then backpedal, you'll get a TON of enemies spawning, and if those enemies spawn more enemies, then you've got your work cut out for you. It also means that you can simply go forwards, walk back and then forwards again on the 2nd and 3rd beacons(The first one was pretty balanced, with you needing to upgrade at approximately the rate that they spawned) to spawn insane amounts of enemies for a TON of energy.
But otherwise, I loved the game, especially this music at the end after I've won. Go piano ftw. I just wish I could download it.