Named Game of the Year by over 50 publications, Valve's début title blends action and adventure with award-winning technology to create a frighteningly realistic world where players must think to survive. Also includes an exciting multiplayer mode that allows you to play against friends and enemies around the world.
Addon, that adds the "Sierra Studios" splash screen, as in WON version of Half-Life
Wondered how long it'd be before someone did this.
Turns out it wasn't long at all!