Some interface suggestions from an Android user:
Move the block description button ('?') to the bottom right (currently it is top right and frequently gets confused for a 'close' button)
Change turrets in some way to indicate the fuel type. Uniform color schemes/shapes/central indicator pixel?
Some way to cancel drag construction before placement. Maybe a dynamic cancel button somewhere on screen.
Menu option to adjust 'hold deconstruct' time.
Menu option to reduce particles in battle and avoid lag spikes.
Show how many of a block can be built with current resources.
Thank you for this game!