This is a key for the Dead Island Definitive Collection, which includes Dead Island Definitive Edition, Dead Island: Riptide Definitive Edition and Dead Island Retro Revenge: https://store.steampowered.com/bundle/320/Dead_Island_Definitive_Collection/

Please note that owning Dead Island Definitive Edition already will mean that you will be unable to "redeem" this game if you win.

Best of luck! :)