When I was growing up, I played on MUD games, which were text-based massively multiplayer games 100% free to play, with no ads or any other kind of monetization, with full staffs of admins, programmers (!!), level designers, and moderators, all 100% volunteers.
Reading that now, it sounds like I'm describing some kind of crazy sci-fi utopia that couldn't even get published because it's too unbelievable.