I’ve been a gamer for almost 4 decades, so I have quite a lot of experience wanting to run games that I remember were a lot of fun and it turns out they are so old they won’t run anymore.

Typically it’s one of 3 things:

• The hardware I have now won’t support it (say, I don’t have a floopy drive anymore, or they’re from an entirelly different architecture such as the pre-PC game consoles). There’s also quirky ones such as games made at a time when CPUs were so slow that the game just runs as fast as it can (which was fine for older CPUs, but not for CPUs which are thousands of times faster) rather than use the system clock to set its tempo.
• The OS I have won’t support it. Say, it’s a DOS or Windows 3.1 game
• The game has DRM which relies on shit which doesn’t apply anymore (for example, OS quirks that aren’t present in newer OS versions).

There are often ways around the first two - for the hardware sometimes you can get modern versions of older hardware (for example you can actually get an external USB Floppy Disk Drive) and if it’s old enough there will be emulators, whilst for the OS it’s either emulators or adaptor layers.

Only way around the third is either a game crack or the game having no DRM to begin with.

Now, outside the transition of hardware architectures (say, from Amiga to PC) this used to apply maybe after a game was out 10 - 20 years. In the Phone-home DRM generation this seems to apply much faster - the game maker just turns off their servers 5 - 10 years after the game is out and now you can’t legally play that game anymore.

All this to say that GOG and Pirates are the only ones fighting the good fight on making sure we won’t suffer this shit some years from now, which is even more important now that we’re in the Phone-home DRM age.