Honestly, you should give it to a friend, or, whomever. You had made a mistake, but, now, someone else can benefit, which, in turn, will also bring you happiness. Pleasant wishes to you.

You could try this thread.

Selling, probably not. Sides it would be considered shady.

Trading? A bit better and less suspicious, though not sure about a $99 code...

I'd love to help you... but how do I know you are not an evil necromancer who wants to enslave all children and take over the world?

Sorry but I have trust issues ever since I had to deal with one such cretin. He was also supposedly just "selling a game code" but in reality he had much darker motives.

The game's $31. $99 is for a physical Collector's Edition and surely the OP is going to keep all the physical junk.

I don't think selling codes is allowed on this forum (there are some regulations somewhere but I never bothered to read them...)

However, you can trade it for steam codes or similar with other users in this thread:

GOG's (General) Trading Thread

Mhmm... That explains the items that don't sound like digital extras that are possible.

His best bet would then be to see if someone has a steam version of the game and if they'd want to trade 1:1.

Or just hold onto the key and buy the game again directly from steam. Maybe give it away to family as a present.

OP, if you can't trade it soon, I would recommend just redeeming it. Unlike Steam, GOG keys have an expiration date. The last thing you want is for it to expire if you wait too long.