You can attempt to redeem an original 13-digit Sierra key on Steam by going to > Activate a Product on Steam . Half Life CD key code where??? - Google Groups
However, here’s what you can do instead: half life 1 cd key 25 digits
Sites like G2A, Kinguin, or Eneba often sell "Half-Life 1 Steam Key (Global)" for $2-$5. These are 25-digit keys. However, proceed with extreme caution. Many of these keys come from: You can attempt to redeem an original 13-digit