My main concern with the game is the lack of sound effects, they provide a feedback to the player when they perform an action in a game and not having them affects drastically the experience they perceive. Second concern I have is how "hidden" the instructions are from the player, if your player does not know what they are expected to do and how they should do it they may quite faster that you can say LDJAM; you need to protect the player from himself by posing an structure that ensures they understands what are they are supposed to do and what is the end goal, for instance, instructions at the begin of the game or better yet a "reduced" experience where they safely can discover the mechanics of your game (but without making a boring tutorial, that is).