Great feedback, thanks!
The curve of the shots is an oddity caused by the max velocity, but they probably should be allowed to go faster. A crosshair is a good idea, as is the idea of a cone-shaped weapon. I considered autoaim, but didn't know how to implement it without it looking weird.
The shield and power were added in the last days so they didn't get much love (due to lack of bytes mostly). As it is, the shield is meant to be a reactive block, used only in desperation. This is counterintuitive since shields in most scifi and video games don't work like that.