Well, what I played from the demo, of course it's a demo, but there's not much to be said right now.
You can walk in two directions and fire at zombies (?) that spawn too much.
Personally I always like to wait until I've got something serious to show for, not that I ever show much to begin with, but it seems like a better approach than to show almost nothing.
Didn't mean to be rude, perhaps we have different standards.
Also, the menu buttons on the demo don't have any text. I think you might have used a custom font? Furthermore, the mouse arrow doesn't show. I have to guess where it is.
Anyway, best of luck.