Some suggestions:
Spacebar: pause game.
I: open inventory.
M: toggle music on/off
S: mute everything
Distinctive melody when final boss appears.
Distinctive sound when a hero is about to die.
It would be great if there was an option for switching off only the music, not both sound effects and music. And it would be very helpful a special music or sfx when the characters are getting close to the final boss so I can come running to my computer and help them with my tapping.
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