I think
What engine did Gmod 9 run on?If the episode one engine and you can run HL2, probably.If orange box engine, probably not.
Source SDK calls it the Episode One engine. :P
heres the tf2 uses diffrent graphics then other valve games it might be your graphics cardalso it turns out all valve games that dont use the origional half life one engine use source
Yes, the TF2 uses a different version of the Source, but all Valve games run on Source, just different versions. L4D uses a separate newer version of Source. TF2 uses a different version of Source. All of them use Source but in one way or the other.