I recently got into fighting games (like: kof - street fighters - Mortal Kombat - Guilty Gear...etc). Now you can pirate the game, and you can play it online with someone if the two of you agree on using same pirated copy and Hamachi for example, but where do you meet these people to play with? are there dedicated forums for online games lobbies?
I don't even know how people with steam copies find opponents online, I just see them mention "the steam lobbies". But from observing people's reviews on their online experience with kof XIII, I understood that it overwhelmingly sucks.
I took fighting games as example here cuz I already know fps games like Counter-Strike 1.6 have sufficient sites like this: https://www.gametracker.com/search/cs/
I remember we used to play pirated Yu-Gi-Oh! using Hamachi, organized through facebook groups, so is that the only hope for these situations? praying to find a facebook group for organized matches of your niche?
Have you heard of Fightcade?
It is for retro games, if we take the example of a classic game that came after 2009, like
kof 2002um
kof XIII
Mortal Kombat X
Than fightcade isn't relevant. But yeah I tried it and it is great for its' purpose