hello, this should be a valid key. ive had this key for years. i also got this in asian steam.
if it's not valid and cannot be redeemed, i apologize!
gl in the giveaway!

also: please do not dispense or sell the games when you receive a game in any giveaway
this doesn't do any favors to us who provide the giveaways and the other people who are hoping to win the game