Hmm
Well, one thing I would say is that it's too easy. I didn't die once, I played for about 10 minutes, got past a "3D" thing.
Seonc - if this is supposed to be an old atari game, the graphics are inconsistent with that type of game. I mean, the mechs are all right, although I think they're too simplified for even old atari graphics. The lazer is a clean line - in an old atari game, it would be pixely. Same with the bullets. The introduction was too high-res too. I would have gone ahead and done the WHOLE thing in atari 2600 style graphics, or none of it. A combination of the two, like you have, is kind of odd.
The sounds are suffering from the same thing. Some sound modern, some sound atari-ish. STick with one or the other.
The gameplay is kinda neat, kinda like asteroids, kinda like something else I can't place. But overall, it's a good idea. It's just too easy.
Oooh! In an old atari game, the entire screen would probably flash when you got hit, or hit something big, or something like that. Definitely it would flash when you died. Does this one? I don't know - I didn't die. Like I said, too easy.
I hope this is helpful to you.