Very good idea and adherence to theme.
Any weaknesses lie in the design, but all of them can be fixed with feedback and time. Controls are clunky, but that may be intentional or a result of which ones I used (WASD+mouse). As others have mentioned, feedback as to what mode you are in now, as well as which weapon, would improve this.
Only being able to fire in eight directions might be fine when you can move freely, but as your movement is limited in this game, I think being able to fire in any direction (such as where the mouse is pointing) would decrease frustration and clunkiness.
Great game!