Just shoot the ghosts.
If they overlap your "sight", they will chase you.
WASD to move;
move the mouse to aim;
LMB to fire
<img src="http://dl.getdropbox.com/u/1218781/img/Ghost%20Buster01.bmp"> <img src="http://dl.getdropbox.com/u/1218781/img/Ghost%20Buster02.bmp">
I fixed the bug with the armor(it's -1 on the screenshot), but I didn't make a new screenshot.
The box between the Ammo and the Weapon Type shows you your "Reload".
You need 10,000(100%) of it to use the last weapon - take a look at the group "Stats and Shooting" for more information.
Here's the cap: http://dl.getdropbox.com/u/1218781/Ghost%20Buster.cap
( if you want, "upgrade" it and post it, I hate taking care of things)