One array for all sounds. One array for all buttons (same order as sounds). One Actor field for correct button (initially set to null). One int field to keep track of the count of how many sounds have yet to be played (initially set to number of sounds, or length of sound array). When Actor field is null and counter field is greater than zero, choose a random index for sound array using counter field as limit; then, move that indexed element of button to the Actor field, and play the cooresponding sound from the sound array; then swap that indexed element in both arrays with the last possible chosen one, currently indexed at one less than the to-be-played value, which should subsequently be decremented. When the correct button is chosen (which is best check on by the act method of the world), set the Actor field to null. You could show some type of confirmation that the correct button was clicked first, if you so desired.