Very fun little game. No idea why people are giving it low ratings.
Story: Lacking, but understandable. I did like that I was thrown right into the game without having to read some long-winded explanation of the universe I am playing in, but a lot of points were confusing until I had finished the level or read some dialogue later on.
Graphics: Superb. Nicely done 3D animation, good drawing. More than decent for a game on NG.
Gameplay: The only really annoying thing I have to complain about is that when I pick up the double blaster upgrade, it nullifies my big-blaster upgrade. I was hoping for double big-blasters. Boo. Other than that, pretty terrific and simple game. There could have been more diversity in enemy attacks.
Nostalgia: I laughed at the invaders boss. The character graphics remind me of StarCraft. Very cool.