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.

21 20

11 40

16 40

20 42

29 44

8 20

21 10

58 21

29 43

22 40

15 10

17 40

89 46

23 41

48 47

13 10