No, the 15-digit activation code that came with your retail copy of Civilization V: Gods & Kings game will work. During the installation process, you may encounter a screen that asks for your unlock code and presents 5 blank "boxes" to type it in. While it may appear as though the game requires a 25-digit code, Gods & Kings will unlock correctly if you fill in the first three of these boxes with the code you received and leave the final two boxes blank.
Have more questions? Submit a request