After we built our game, there is still one issue existing- couldn’t quit the game. We can simply add 1 line to code to solve this situation.
Open GameManager script, in Update() we can add a line to it.
Application.Quit() will handle exiting the game when player press escape when game over.
Besides that, we need to create a text UI to notice our player can press escape when game over.
Duplicate Restart_text and rename it as Exit_text, then drag it slightly under Restart_text. Then edit the text content.
Open UIManager script, add a new variable to storage Exit_text. Then disable & enable it in Start() and UpdateSprite().
Back to editor, drag the Exit_text into variable holder in Canvas.
After all the setting, you need to build the game again to check the function.