Valve landmark first-person shooter Half-Life has been ported and quietly released for Mac OS X and Linux.

While Valve hasn't made any official announcements about the availability of Half-Life for other platforms and currently lists Windows as the only supported OS, the Mac version appears in our Steam library, installs and runs well. The original Half-Life, first released in 1998, has been one of a handful Valve games that hasn't received a non-Windows port since the developer began pursuing Mac and Linux development.

The release of the original Half-Life could pave the way for older Valve-published titles like the original Counter-Strike, Team Fortress Classic and expansions Opposing Force and Blue Shift to come to Mac and Linux.

Half-Life is currently priced at $9.99 on Steam.

(Thanks, Espen!)