We also have two friends with dedicated LAN party basements. But it's way more casual. They have 10 old office PCs each that were available for pretty much free. We meet around every two months to play old games. Stuff like Half Life 1 DM.

I,ve also started playing with Linux and Lutris to pre-install old games. Still need to figure out the netboot part.

Also regarding the Steam / Epic situation: Steam has a PC Café program where you can buy licenses which then can be used by people with their own steam accounts while they are in your local network. I set it up once and it is a neat feature.