I know this is a little odd but I can't find any good answers on the net and this is my last resort to see if the knowledgeable folks here can offer any definitive answer.
I have changed the gravity In my CS:S server, and single player games of HL, HL2, HL2Ep1, and others because the gravity cvar is not hidden. When we had a TF2 server and in our current L4D servers we change the gravity using sourcemod to expose the cvar .
Since OrangeBox was released, Valve has puzzled me and my game play by hiding the gravity cvar. So the question is...
Is there any way to change the gravity in Portal and/or HL2Ep2? Is there any kind of mod that can do this?