As a mischievous high schooler, I was a huge fan of classic con movies like The Sting, and legendary hustlers like Titanic Thompson [1]. One of my favorite stories about him was when he took a standard horseshoe pit, extended it by a foot beyond regulation, and practiced on it for months. Then, at the appropriate time, he challenged a professional horseshoe player who unknowingly playing on a subtly modified field couldn’t understand why all their throws were falling just short.
To that end, I decided to pull a harmless little prank on my buddy.
We were friends with the owner of the local arcade, so after closing one night, I talked to him about a setup I wanted to try. With his permission, I took some adjustable furniture risers and placed them under the back two legs of the Medieval Madness machine.
The result was a subtle increase in the incline (just a few degrees) but it made a big difference in gameplay, especially for someone attuned to the machine’s usual angle. Visually, the machine looked completely normal and indistinguishable from the others. It was nestled between other games, so even if someone had known to look for a difference, the risers were virtually invisible.
Both the arcade owner and I spent the rest of the evening practicing on the steeper table. Naturally, we challenged our friend to play Medieval Madness the following day.
Their game was totally thrown off. I managed to get close to their score which under normal circumstances would’ve been borderline impossible. I didn’t quite pull it off, but I got close.
They were still incredibly skilled, but I remember them muttering under their breath, clearly irritated at missed shots, failing to hit the usual ramps, and even some inexplicable ball drains. I think if they'd played longer they would have swiftly adapted. My armchair analysis is that professional pinball players probably have to subtly adapt to the fact that even the same game across different tables will have subtle variances (strength of flipper solenoids, etc).
I never did tell them what happened.