Many players install the game using the key on their CD sleeve, launch the game, click "Multiplayer," and then stare blankly at a field asking for a "Multiplayer ID Key." They re-type their CD key, and it fails.
While the single-player campaign was a masterpiece of tactical decision-making, it was the multiplayer mode that built a generation of e-sport hopefuls. The intense 16v16 battles, the clunky but satisfying cover system, and the strategic use of the Cross-Com created an addiction that dial-up and early broadband connections struggled to support. Ghost Recon Advanced Warfighter Multiplayer Id Key
You don't need a Multiplayer ID Key to be a Ghost. You just need the will to fight. Many players install the game using the key