Minor QoL Update

As per requests, I've made some minor changes to the experience of control and interface:

• Clickable/touchable area has been extended. Now you can click anywhere below the gameover line.
• Restarted button is now available during the game. Hold the restart button to restart the game.
• Changed the volume button to toggle between "high", "low" and "mute" instead of only "on" and "off".