Hey hey! Cheers for the great feedback. It's as if you read our minds, the next update is going to include WSAD controls :D but not sure about being able to move and shoot - part of the tension is having to stop and aim with the Zombies (and soon to be other foes) gaining on you. If you can move and fire, a lot of that tension would be removed and the game too easy do you think?
But you're right, WSAD does add a lot to the gameplay...
We can even leave the mouse click-move stuff in, I find myself switching between the two.