Hi, thank you for the giveaway, Im your winner! :D
Stoopid question, just to be sure before viewing your key: are you sure that it is for Riptide classic and not for Riptide Definitive Edition? Im asking because they are different steam apps, and if I activate the key, but its for the other version I cannot mark as recieved, otherwise it will be flagged as a non activated gift for me. Thx in advance for your answer!

https://steamdb.info/sub/26345/
Look please this reference. This game already is not present in steam. If fear problems from steamgifts, I can delete this game. To me to delete a game?

Okey cool, thanks for the answer, activated fine and marked as recieved!