As opposed to Steam, GOG will let you create backups of your games that will survive GOG itself. GOG provides offline backup installers that don’t need a launcher, internet or anything.
I always tell everyone to at least get a fully DRM-free copy of their favorite childhood gaming memory.
Well, you’re here seemingly not realizing why studios don’t give a shit about preservation. As we can observe in the real world, the branding opportunities and PR are not worth it to them 99% of the time.