add restartNewGame
add polyfill for the local storage
display the score in the when the game is end. If the score is 0 then show '--'
add css for the game end scene
add button to try again when the game is over. and update the best score.
get the best score from the localStorage in a function
setup a new best score and access the best score in the game manager file
call the game over function when the game is over