Bowling experts tend to get into a single-minded groove. They find one way of rolling the ball that works for them, and they do that, frame after frame, game after game, with no incentive to learn new techniques.
Hole-bowl alleys make bowling more complicated by opening up gaping holes in the middle
of the alley during each frame. (Sliding trapdoors under the wood serve to open or close the holes).
Skilled bowlers will have to roll the ball with a controlled curving trajectory to dodge the holes but still hit the pins. And they would best learn two or three different approaches, as if one of their normal "routes" is blocked, they will have to use another.
There are more holes in each progressive frame, until by the 12th frame (if one makes it that far), the alley looks like a giant strip of Swiss cheese.
As an added element of fun, you do not get your ball back if it falls through a trap door. It simply falls 20 meters down onto a basement floor and is destroyed.