This is great! Amazing polish. Super fun to play.
Also, the cubes moving on a grid like rooks, while you drift around freely, was a super creative idea that worked really well- I had to completely change my strategy and plan carefully while they were around!
A few small notes, in case they're helpful:
- The shop was off-center from the screen, so I couldn't see how much the upgrades cost.
- Having the shop on the Tab key was a little inconvenient, especially when 2 squares were around, so I couldn't mess up my movement. Perhaps Right Click or Spacebar would make opening the shop more streamlined.
- The turrets made the gameplay more interesting, however the only way I ever saw one was by specifically heading towards the bullets, specifically to see what they looked like. Otherwise, they are only experienced as "annoying bullets that can be quieted down by shooting offscreen for a few seconds."
All in all, terrific submission. Peace!