Gmax is teh lite free version of 3Dsmax, it doesnt have a feature that allows game makers to make there games Gmax compatable, what is ment by that is that the developer can write custom export and import plugins for Gmax so that players can export there meshs into formats supported for games such as .mdl, .obj and .ase and such in such. Gmax has no native support for such formats and its own format is all but usless.
The major problem with letting players make custom \"things\" in a 3d programme then uploading them for use in a game is that every one has to down load the \"thing\" in order for them to see it ingame, and since every one would want to do so thered be some major network slow down. I personaly have little faith in the average players abilitie in 3d programmes, especialy after seeing lots of crude primitives used and posted on this boards in ages past... polycount people... still find it funny people cant figure that one out for themselves, guess its an ignorance in the process of game making... oh well.
nice idea on paper, damn stupid in practise.