Sweet game.
Takes a great deal of concentration, but not overly difficult. The great part is that you're given free reign- there's no "right answer". It was pretty cool how you could make patterns and such, and overall I have to say it was very satisfying to finish. Hard mode isn't really worth the 60 second push, but otherwise, very nice!
Maybe a random level generator could keep things interesting?
~VelvetDarkRocks~