Nice puzzle game you have here, it features different levels of difficulty and different modes of play. There are things you can improve and add though.
~ A mute button.
~ A pause button and menu.
~ A freeplay mode that isn't locked.
~ A graphics button.
~ Better artwork in the menus.
~ An ultimate goal or plot.
~ Tiles or powerups that you can use that increase your maximum amount of moves.
~ Something to let you fight against your enemies.
~ Tiles that are impassable for a few seconds then passable for a few seconds (like a fire trap or a hole in the ground that opens and closes).
Things you did well:
~ Great programing.
~ Decent artwork for some things
~ Music was somewhat fitting.
~ You have highscores.
~ Enemies and keys are included.
~ Made it necessary to think before doing anything movement wise.
Nice game, with a little practice, it can be even better.