Half-Life や Counter-Strike が無料でできるようになったらしい.
Steam でできるゲーム
Half-LifeCounter-Strike
Team Fortress Classic
Deathmatch Classic
Opposing Force
Ricochet
Dedicated Server
Reference
Welcome to Steam (Official site)http://www.steampowered.com/
Download
http://www.steampowered.com/?area=getsteamnow