How to start the game?

Black Mesa Archive Help!
#21

Close Steam then reopen it?

#22

At the top of the Steam window, click the “Steam” menu and choose “Exit”. Then restart Steam with the associated icon. If you do not have the icon:

Go to:
If in a 32-bit Windows, C:\Program Files\Steam and run Steam.exe
If in a 64-bit Windows, C:\Program Files (x86)\Steam and run Steam.exe

Once you’re back into Steam, you should see Black Mesa in the list of installed games. Double click to run it like you would any other game in Steam.

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.