I kept the graphics simple on purpose. I was going for a simple, clean, utilitarian feel to the game. Any suggestions as to how to accomplish this while making it more professional are welcome.
You should take a look at Kenta Cho games: these games are well known for having a retro look which delivers a lot in terms of style. They are an excellent source for gameplay inspiration since these games incorporate almost all shoot'em up concepts out there. Still about style, Darwinia springs to mind too, or of course games like Geometry Wars (Grid Wars was already pointed out though which shares the same style). Otherwise you could take a look at Mutant Storm but its style is more complex albeit wonderful.
http://www.asahi-net.or.jp/~cs8k-cyu/index_e.html
http://www.introversion.co.uk/darwinia/
That was my original idea - left stick moves, right stick points and shoots. However, not all people have compatible gamepads on their computers - plus in Blitz3D there is no way to get the second set of JoyX and JoyY, like in BlitzPlus. If anyone knows of a way around that, it'd be very helpful.
I usually play this kind of Robotron like games using the keyboard cursors for movement, and WASD for shooting. I am a lot more responsive that way than by using a dual analog controller or mouse + keyboard.