SimonG: That is just on top of my head.
wpegg: You must be a very tall man with all that on there :).
That's what
she said. (That joke never gets old, even twice a day).
wpegg: I was aiming more at an information exchange portal. So there would be no direct knowledge of what the information being exchanged was. This would further complicate things as then the governments could use their anti-terrorism corruption to actually take it down, but at that point the world ends (yes, I have that button).
If you would make a very basic site. More of a forum with a good thread structute, you
might get away with it. I mean, piratebay is running on this argumentation. Memeber get voted on succesffull "deals" and you simply use a simply "question/answer" structure like GOG has.
The user, however, would than be in the hotbed. The point is, we are all cushioned by the law, because we are "end users" or "consumers". After a certain amount of "deals" a member would become a trader of reseller, which could lead to all kind of nasties. Steam and GG could shut down their account (rightfully, btw, you are in a deep violation of the SSA).
A working solution would be that the account on your trade page isn't linked to a GG and Steam account. Each member would need "throwaway" Steam/GG accounts that could be used until it would be noticed. Ideally the "trade site" would also give out email adresses, because you would be burning through those rather fast. But eventually email form that site wouldn't be accepted anymore.
Than you would need an anomynous payment method (paysafecards, eg) to avoid traces through payment options. Because in a last ditch effort Steam/GG
could try to get damages (and after a quick breakdown in my head) and they could just maybe make something stick. At least there would be enough of a risk to avoid that.
All in all, that
could do it.