What to do when when you win a game and activate the key...

If the code was invalid/dupe/already used let the creator know and don't mark received. The creator can then provide a new key or ask you for permission to delete the giveaway.

What proximus said. They may ask you for permission to delete the giveaway if they don't have replacement, and the usual courtesy is to allow the giveaway to be deleted. (While you could refuse deletion, you are unlikely to get the game anyway)

^^
Also if u received correct key and decided to mark as received and not activate this key (for example - reselling) - u will enjoy short 5-days-long vacation

demand a working key ^^

Thanks everyone. Admin/mod can close this topic now.

I've accidentally given a duplicate key before, and it horrifies me every time - definitely contact the giveaway creator. If I find I've given a bad key, I do everything I can to rectify it.

You marked all your wins as activated, so i dont see why are you asking.
+You will just get on lot of blacklist because of your really bad ratio.