As the title says, some dude has a copy of the HL1 Alpha and uploaded it on Reddit. Some really cool stuff in there.
Half-Life 1 Alpha on reddit.
This edit will also create new pages on Giant Bomb for:Beware, you are proposing to add brand new pages to the wiki along with your edits. Make sure this is what you intended. This will likely increase the time it takes for your changes to go live.