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.
Nice, but you should move this from addons to files.
It doesn't show in Steam when I restart.
You should alter the liblist.gam file so that the "game" value is something other than Half-Life: Opposing Force, otherwise it's not going to show up for people who already have Opposing Force in their steam library.
EDIT: Nevermind, it still didn't show up. Launched it through the .exe and it crashed to desktop during the intro.
For me the intro works just fine, but Boot Camp is broken as there are no NPCs there.