Unlike a modern Steam key that simply authorizes a server handshake, the Opposing Force CD key carried contextual weight. It was a Sierra key, not a Valve key. This meant it had to be entered into a separate launcher that checked a local writable registry file ( HKEY_LOCAL_MACHINE\SOFTWARE\Valve\Half-Life\Settings ). If you lost the key, you lost the right to play online. There was no "account recovery." There was only a dusty support number on a website that no longer existed.
occurred with the transition from the World Opponent Network (WON) to Redemption Capability: half life opposing force cd key