This tutorial teaches you how to let Gmod9 appear in your Steam library
How to let Gmod9 appear in Steam (mostly lets you press the Play button for you).
Go to your Steamapp/sourcemod/gmod9/
Open your gmod9's txt document called gameinfo.
Just Change the the steamappid to 215 and restart steam and it will appear at your steam library!
Many keep saying that gmod9 is not showing up at steam library so I decided to add this tutorial to let people play gmod9!
Considering the fact that GMod 9 is outdated and doesn't support a large majority of the mods that came out for GMod 10 and later, people would just be better off getting a copy of the game on Steam instead.