Short and straightforward and fits the theme well. Could make for a decent puzzle game if you pad out the levels, though I don't really feel like there's anything about this I haven't seen before in other games. Props for doing all the work yourself, though. I know how hard that can be.
One thing that stopped me from giving it five stars for gameplay is that selecting the cubes was a bit hit-or-miss, having to wait for them to be selected. I feel as though a bigger selection radius would help since all your cubes are far enough away from one another that there's no risk of selecting the wrong one.