button.mp3
    CC-BY distillerystudio (http://freesound.org/people/distillerystudio/sounds/327732/)
crack.mp3
    CC-BY InspectorJ (http://freesound.org/people/InspectorJ/sounds/352193/)
step*.mp3
    CC-BY InspectorJ (http://freesound.org/people/InspectorJ/sounds/339325/)
wilhelm.mp3
    CC-BY-NC Syna-Max (http://freesound.org/people/Syna-Max/sounds/64940/)
clock.mp3
    CC-BY TreasureSounds (http://freesound.org/people/TreasureSounds/sounds/332629/)
win.mp3
    CC-BY LittleRobotSoundFactory (http://freesound.org/people/LittleRobotSoundFactory/sounds/274183/)

Other sounds: CC0