Want to re-familiarize yourself with the Half-Life franchise? Or interested in trying the series for the first time? You'll be able to, easily, thanks to a new promotion held by Valve. In order to hype people up for the imminent launch of Half-Life Alyx, all the games in the franchise are free to play on Steam, for a limited time. Running from today until Alyx's release, Half-Life 1, Half-Life 2: Episode 1 and 2, Source, Opposing Force, and Blue Shift are all available for Steam owners to download. These aren't free to keep, but you'll be able to play them without cost for the next two months.