if the game has LAN, then it's typically possible to use that to play online (via a P2P VPN service like Hamachi, Tunngle or GameRanger). If it allows dedicated servers, those can also be used (as long as the game's popular enough for someone to host them).
However, if multiplayer can only be done through the centralized servers of the devs/publisher, it gets a lot more complicated - in some cases people figure out how to essentially emulate the server connection with their own private ones, but for a lot of games it's not possible to play them online.
So most older PC games are perfectly viable, since having LAN and dedicated servers was pretty much mandatory back in the day, but a ton of more modern multiplayer games had those features stripped out.
if the game has LAN, then it's typically possible to use that to play online (via a P2P VPN service like Hamachi, Tunngle or GameRanger). If it allows dedicated servers, those can also be used (as long as the game's popular enough for someone to host them).
However, if multiplayer can only be done through the centralized servers of the devs/publisher, it gets a lot more complicated - in some cases people figure out how to essentially emulate the server connection with their own private ones, but for a lot of games it's not possible to play them online.
So most older PC games are perfectly viable, since having LAN and dedicated servers was pretty much mandatory back in the day, but a ton of more modern multiplayer games had those features stripped out.
Thanks for the answer