Publishers are absolutely terrified "preserved video games would be used for recreational purposes," so the US copyright office has struck down a major effort for game preservation
I’m sitting on the RetroAchievements collection over here. It is my single most seeded torrent, by leaps and bounds. I went with RA, because it means I can throw any of them at RetroArch and the RetroAchievements integration will work without having to fiddle with game versions. It also has a surprising number of ROM hacks and homebrew.