A game key is a serial number consisting of letters and numbers which can be used to activate a game. Activating a game key is possible on gaming platforms like Steam. A game key can only be exchanged for a game once, after which the game is assigned to your personal account. This ensures that you can download and play the game through your account even after you have deinstalled or deleted the game from your pc. Game keys are also known as game codes, activation codes or product codes.