It seems like you are going for a spatial puzzle game that demands speedy dexterity and decision making. These types of game are typically played over and over again and so it's a nice accommodation for those players to allow them to restart quickly and conveniently. Since playing the game is done using the arrow keys, it kinda breaks the player's flow to have to click an onscreen button with the mouse in order to restart the game. My suggestion would be to make the up or down arrows restart the game so that players can treat the fail-state as nothing more than a pause to their flow.
I also noticed that the piece-type cycles in a consistent way. If this is intentional, it would be nice for players who are not very familiar with the game to see the order of pieces they are cycling through. This could be done with a visual list of piece-types with some sort of visual spotlight that highlights the selected piece which shows the player how many left arrows they are away from the shape they intend to use. It would allow for even more mastery if the left and right arrows allowed players to cycle back and forth moving the highlight around a consistent array of shapes.