A demo build of 1997 alpha found on a disc intended for journalists at the time, apparently, has been shared on the internet by Reddit user Jackaljayzer (via ValveTime).
Jackaljayzer has put the contents of the disc up on the web and is auctioning the disc on eBay. You can download the alpha right now from this link. To play the alpha delete or renamed the “…\Half-Life 0.52\Half-Life\Opengl32.dll” file and then run “…\Half-Life 0.52\Half-Life\enginegl.exe”.
