Are you aiming to play the or online multiplayer ?

During installation, a pop-up window will request the . You must enter it exactly as it appears, including any dashes or spaces. 2. Digital Versions (Steam/GOG)

For modern users, installing via digital platforms is recommended.

Understanding Quake 4 CD-Keys and Activation Released in 2005, Quake 4 remains a classic sci-fi first-person shooter. Developed by Raven Software in collaboration with id Software, the game requires a unique serial code, or CD-key, for installation and online multiplayer verification. The Purpose of the Quake 4 Serial Code

While you could play the single-player campaign offline, the "Master Server" would verify your key when you tried to join a multiplayer match to prevent multiple people from using the same code simultaneously. The Shift to Digital Distribution As platforms like took over, the "Serial Code" evolved. Automatic Activation: