Good controls and fun graphics/theme for a rush-hour game. But some levels seemed too large and unconstrained, and others like level 6 were a bit tedious when moving a line of ships. I'd recommend either making there be fewer, larger ships in that level, or programming the game to allow ships to push other ships when moving.
Interestingly, Level 4 seems to have some ships offset by half a block, but it was very subtle and seemed like maybe even a glitch? Would've been interesting to see that mechanically explored more.