Half-Life: Alyx is coming in March, and Valve is celebrating early by making all games in the Half-Life Series free to play for Steam users, from now until the day it launches.

If you already have Steam installed, you can click the following links to start playing now.

• Half-Life
  
• Half-Life 2
• Half-Life 2: Episode One
• Half-Life 2: Episode Two
  

If you don't have Steam, you can download it here.

Half-Life: Alyx is set before the events of Half-Life 2 and the episodes, but the games share characters and story elements.