If you are specifically looking for a code for the original Half-Life 1 (1998), you are likely encountering a discrepancy. The original Half-Life games (and the Counter-Strike 1.6/WON era) utilized a 13-digit CD key format (usually arranged as XXXX-XXXX-XXXX ).
Type in your 13-digit key . Steam’s activation window is designed to accept various lengths, including the classic Half-Life format [4, 5]. half life 1 cd key 25 digits