Self-explanatory; this is specifically for slot machines found at a variety of locations, usually casinos. It can be assumed that most of them will run a variant of Linux on x86, with occasional ARM outcroppings.

This specific one is a fairly average industrial PC that is running a custom version of Debian

The state-operated slot machine company of Finland has machines which run Linux, both on the machines themselves, and the development environment for the machines. Props to Finland for embracing FOSS here!

https://nibblestew.blogspot.com/2018/02/looking-inside-linux-powered-slot.html