I bought a key code through G2A for starpoint gemini 2 and I don't know how to activate it on GOG...

Buy the game direct through GOG

He will, once his first game is revoked due to credit card fraud...

Anyone want to bet on how soon it's going to be revoked?

G2A is not a legitimate seller of GOG codes, it'll probably get revoked sooner or later.

We'll see who wants to "khs" when the key gets revoked. :D

PS: Don't buy GOG keys from G2A, ever. Hell, don't buy anything from G2A and the likes, ever.

Ignoring the morality of the G2A marketplace for a moment, the historical lowest price for Starpoint Gemini 2 is the one it's currently being sold on GOG at, or $8.74. If you paid less than that, you are most likely being scammed, since why would someone sell it for less than he bought it. No, regional pricing doesn't count for gifts on GOG, the buyer pays the CN price (or his own, whichever is higher).
If it was a bonus code instead (18 characters instead of 20), it might be legit, but I don't recall any such offers recently.

Either way, enjoy your game, and hope nothing bad happens.

Seriously!?

I own "Faces of Death" on DVD and even I think that comment is offensive. :P

And I know I told you already, but I am a HUGE Ambrose fan.

Yep. Most people would find that offensive.

Off-topic: Ambrose needs another title run. I'm not liking the Baron Corbin angle that much.

You are being an ungrateful little shit to people legitimately trying to help you.

AFAIK, G2A is a grey-market key reseller who buys keys from people who sometimes use stolen credit cards to purchase the keys; if GOG is contacted about a stolen credit card used, it's likely they'll pull the game from your account. If the game is revoked, contact G2A, not GOG, for a refund. And either stick to Steam keys on G2A or buy directly on GOG.

Except you can't redeem keys that have been used before. So they're selling something under market price that they have never used, and has never been valued as cheap as they are selling it. That's pretty much a dead giveaway. Hope you get to download your game before the key gets revoked. And you should probably stop being a grade A dick to people trying to help you out.

If one could sell items they've already redeemed in their library, I would have thought that as a possibility. However, neither GOG nor Steam offer said choice.

As I said, I'm ignoring the morality.

Once more, I sincerely hope nothing goes wrong with your game and that you do enjoy it. I'm only pointing out potential flags to look out for.