From Press Release:
An upgraded experience, new features, archival footage. and even a documentary! Join us as we mark 20 years of Half-Life 2 by celebrating the community of players who have been enjoying it (or discovering it, or even re-discovering it) since November 16, 2004.
We created a new webpage to showcase all the updates in detail, but you can also read more in our blog post, and from now through the weekend (until November 18th at 10am Pacific) Half-Life 2 is free to own, so if you’ve never played before, grab it now and keep it forever.
