Hey, people, I want to tell you that I have the Disc Version of The Original of SC3000. So here's my question here, if I owned the Disc Version of The Original of SC3000, Could I have the GOG Key for Unlimited for free if I had owned it?

It could also probably do to the others had owned the disc edition of both Original and/or Unlimited version.

Reclaiming games in this way only works for the following titles: https://www.gog.com/reclaim

But the Reclaim Feature hasn't been updated in a year, the last time the reclaim feature was updated is the day of it's launch, APR 1, 2015.

Precisely.

Since SimCity 3000 Unlimited isn't on that list, you can't hope to reclaim it through a CD key.

It would not have stayed on the bottom of the main page for so long, and news posts surrounding it would have had a different tone.