Half-Life series free-to-play via Steam until Half-Life: Alyx release
Half-Life: Alyx due out sometime in March.
Half-Life, Half-Life 2, Half-Life 2: Episode One, and Half-Life 2: Episode Two, as well as Half-Life: Opposing Force, Half-Life: Blue Shift, and Team Fortress Classic are free-to-play on Steam until the release of Half-Life: Alyx in March, developer Valve announced.
The virtual reality-exclusive Half-Life: Alyx is set before the events of Half-Life 2 and its episodes, but shares characters and story elements. Thus, the old games are being made available for everyone to play for free before the release of the new game so that players can get maximum enjoyment out of the new game.
Read more about Half-Life: Alyx here.