This is a reproduction of the objectively best ever game controller: the Uo Poko cat paw joystick. It attaches on top of the balltop on a Japanese-style joystick and turns it into a cat's paw you can hold on to. There's no better way to play video games.
Uo Poko is basically "what if pachinko, but a puzzle game"; you control it by pulling down on the joystick to pull the plunger, and let go to shoot. No buttons, no other controls, just pull and let go. So the cat paw is actually a pretty great practical aid; it gives a grip that's better to pull down on than a normal joystick.
I commissioned this art specifically for my stick.