Thank you for trying it out and thank you for the feedback!
We agree the turrets and upgrades are rather hard to control simultaneously, and we are working on a version which will have key-presses in order to select upgrades instead!
I think the problem is that the W/S and Arrow keys are so far apart you have to use one hand for each making it hard to do anything else. I would suggest maybe binding the turrets to W/S and E/D instead so you can control them both with one hand and use the mouse with the other.
