Valve officially delisted from search results in late 2023 to prioritize the original 1998 version as the "definitive" experience for the series' 25th anniversary. Ways to Play Half-Life: Source
: Retail disc versions from 2004 are often hosted on the Internet Archive for historical preservation, though these may require original CD keys or specific patches to run on modern systems.
When looking for free PC game downloads, it is strongly recommended to use trusted platforms to avoid malware:
: Use Steam, GOG, or Humble Bundle for safe and legal downloads.