This is a GA to celebrate Birds Cakeday :)
Enjoy!
http://www.steamgifts.com/discussion/iFQzk/birdcutes-special-birthday-event-a-lot-of-giveaways

You will find your game key here : http://www.steamgifts.com/giveaways/won

Please don't forget to activate it on your own account and to mark it as received :)