I liked being able to upgrade but also was confused at.. how much I can upgrade and how to place the guns so they fire? I'm not sure if I did it right, but I ended up with a big thing that still only fired one bullet at a time.
I saw your other comment about color and that's fair, but I think you could still use some different shades of gray/white/black to distinguish things. At some point I totally lost my ship in the blocks and it's also hard to tell which bullets are mine or the enemies'. Pretty neat though