I suggest adding a slot machine to this so that the belt opens only if 4 identical symbols appear. And the game time depended on which symbols fell out. From 30 seconds to 30 minutes.

22 11

33 21

58 45

47 42

40 42

38 42

21 11

42 46

41 12

21 2

29 42

39 12

15 11

23 11

43 43