Simplistic concept, mechanic and graphic, good sound design as well, however, I quickly found myself losing the motivation to keep going, but that may be a matter of personal taste with puzzle games. If you are interested in that segment of the demographic, try infusing *a little* lore/story/narrative and make them thematically appropriate in the level design, it won't be an easy task, but I think it will help giving "meaning" to what is currently pure mechanics.