I also struggled with the movement controls, and basically never felt a need to use the "circle strafe" maneuvers on "a" and "d". The aliens also seem pretty bugged. They all just cluster around the middle and nothing happens. The game just seems to end when you run out of ammo, and it looks like there's no way to get more.
Sorry about the clunky controls, they are more intuitive on the 360 controller. I should've used the cardinal directions for the wasd movement (and not just the controller movement as it is now).
And thank you so much for the comment and the review though :) The game is currently unfinished so you can't die or lose yet, nor can you get score. When Zombies reach the middle they will kill a survivor in the cave and you will lose one life. Ammo drops are going to be power-ups that you find as the time goes by, and when you are out of lives and then die you will lose.
I plan on adding these features to finish up the game sometime either this week or next. Thanks again for the comment :)