hl2 not detected

[Jesse Pinkman]

Apparently this game requires you own Half-Life 2 and won't run without it.... BUT I DO! I have the game on Steam. Any way I can prevent this error from appearing?

[Facepalm Full O' Napalm]

Is it installed?

[von dooble]

check if its installed, or maybe youre just doing it wrong

[Jesse Pinkman]

Yes, its installed just not registered in library. I have to launch episode 1 with special parameters to play hl2

[Snoopy]

Are you sure you have Half-Life 2 and not Half-Life 2: Deathmatch, it's not the same.