I played your game, and I think there's real potential once you add in different kinds of enemies, weapons, upgrades, and such. An easy way to add some challenge would be to make an enemy that is similar to the one that currently exists, but it shoots bullets at you as well.
There are ten levels, but they all play identically. I think your demo would be better received if you either cut down on the levels in their current form, or add something to later levels to differentiate them from earlier ones.
I did notice that the controls (when I was able to figure out what they were) state that WASD moves your character around, but when I played the game the arrow keys moved me instead.I would suggest making ENTER a selection key, because when that didn't work I kept pressing random buttons to find the one that did. You could also use the mouse.
I would also recommend that you get rid of the background tiles with the white lines you have in the menu - it makes things hard to read.
I don't care so much for the music, but that's more a matter of personal taste.I envision a more techno-inspired direction given the theme...or maybe you could remix Moon Patrol's theme and really dig into those old-school roots of yours. :)
Good luck with development - it's clear that this game is very early in development, so I'm sure it will be so much better well after this review is written!