it's always nice to play a game of tetris. you could probably improve the player experience by adding effet when the player completes a line and more effect when he completes a tetris (4 lines in one mouve). Also it's more fun to give 100 points when a player does something that to give 1 point, so having two 0 at the end of the score can make the game more rewarding even if it's impossible to gain less that 100 points at a time.