Does Half Life Opposing Force require half life?
 

I've heard it doesn't, but when the setup starts, it gives me the error that Half Life is not installed, and the setup aborts. Even when i install half life, it still gives the same error. Funny thing is, the other expansion Blue Shift works perfectly without even installing Half Life.

:/ try it with another half life...

uninstall everything and try with a different half life version, i have a spanish version and never had a problem with it , i have blue shift, opposing force, decay, sven coop 3.0 , and they all work perfectly..

default install location for Half life as in C;----/program...
maybe it don't see it in other drives if install into like E-Z dive
only guess here

bingo, got another copy of half life from a friend(it was hard to find it), and opposing force works. Great series. Has anyone played Decay on the pc?