achievementssteam
I was browsing my Steam library, and I noticed that one of my games had a glowing gold border around the achievement picture.
Originally, I thought that it was to tell me I had a new achievement, so I tried clicking on it, but it just opened the full achievement list, which is what you see above. I tried clicking on it again, but no change.
What does this gold border mean?
As of the latest update to Steam, you can now PERMANENTLY remove games from your Steam account!
You can browse over your entire library and choose which software you'd like to permanently get rid of. But note, once you have removed a game from your library, it's gone permanently, so if later down the road you'd like it back you'll have to purchase it again.
You'll also need to watch out for some other issues. The thread linked above has noted that if the game is part of a bundle (HumbleBundle, etc.), removing one game from a "package" may require you to remove all the games from that specific bundle.
You probably could have unlocked it with motionJoy if you had done so earlier.
As per the SteamMachines page:
On October 25th, the list will be locked. So complete the quest before then!
Since that date has come and gone, you seem to have missed your chance.
Best Answer
If the achievement has below 10.0% global completion, it will glow gold.
Looks like this was added sometime around September 2019. Example source: https://www.pcgamesn.com/steam/gold-achievements
I didn't find an authoritative source for this, but 10.0% as the cutoff matches the screenshot and also my own games.