I have added a few old PC games and have a few more to add in my Old Games store: https://www.ebid.net/uk/stores/Old-Games. Re-live your misspent youth! Quite a few Windows XP titles, some Vista / Windows 7.

Notes / caveats: None of my PC games require an online account to install or play, e.g. Steam key, they are stand-alone CDROM or DVD-ROM originals. They may include a key required during installation (no online connection required) or they may have disc-based protection (disc is required to be in the CD/DVD drive to play). As should be expected from older games (and this would be true if the same games were purchased through Steam or other online retailers) some online features such as multiplayer may require an account to be created or these online features may no longer be available (e.g. the multiplayer servers may have been retired).