Thanks for trying it out, and I appreciate the feedback. I will take it into consideration. I was concerned at first about the movement rate with the keyboard, because the sprite that I use for the turret only has a limited number of "angles" that were drawn (I did not draw the sprite myself). I thought if it took too long to move from one side to another, that it would negatively affect gameplay.
The mouse should work, though. The way it works is, when you touch an area of the screen (either with your finger or clicking the mouse pointer), the turret will start moving in that direction. And then shooting can only be done by pressing the red button or touching/clicking the turret itself. I admit this might not be obvious to the user at first, but rather it's something that could be figured out just by playing with the game for a few minutes.
(In Construct, I set "Use mouse input" to Yes.)