Back in the olden days, when we used kerosene-powered computers and it took a three day round trip to get IP packets via the local stagecoach mail delivery, we still had games even though Steam didn't exist yet. :b

We used to transfer software on these things called disks. Some of them were magnetic, and some of them used lasers (you could tell them apart because for the laser ones it was usually spelled "disc" with a "c").

Anyway, those dis(k/c)s mostly still work, and we still have working drives that can read them, and because the brilliant idea of making software contact the publisher to ask if it was OK to run had only just been invented, we can generally still play games from the period that way. Some people kept their old games, but others sell them secondhand, which I believe the publishers still haven't managed to lobby successfully to be made illegal, unless I missed a news report.

Even if you can't get the original physical media for a game, sites like GOG sell legal digital downloads of many old games, which are almost always just the actual old software wrapped in a compatibility layer of some kind that is easy to remove, so you can usually get the games running natively on period hardware/software. Finally, some nicer developers and publishers have officially declared some of their old games as free for everyone to play.

There are still legal options for playing old games on old systems.