Potential.
I went looking through the other stuff, expecting to find things to blam (all but a few items in NG are worthless), and I found this. Now, reading through the reviews, I thought that I'd probably give it a one, being lenient. I ended up giving it a 3, in spite of myself. I thought, "You know, this isn't bad for a first try. There's potential here, much more than many pieces from established authors." So, I added a point. Keep up the... no, actually, keep this up and we'll blam you to pieces. But judging by this compared to much of what I've seen, you'll do well after a few pieces.
Now, for more informative parts. I liked the first alien, and the gun, and the warthog. The gunner alien (on the warthog) looked kinda odd. The warthog should not have been destroyable, the aliens in the warthog ought to have been killable (in the game, the passengers of a vehicle can be killed without harming the vehicle). The animation of it blowing up was pretty good, at least. The crosshairs is a big thing that some other pieces actually manage somehow to forget.
The biggest two things here is that:
A. The enemies don't hit you.
B. There are only two different enemies that loop.