errm, Gmod didn't have portals, the Half-Life team made them, and as such Gmod can use them...
Back on topic... I think what ladiios was saying is possible, but I think it would lag to all sorts of interesting levels of hell.
Patizan, stop fighting, you did start it by yelling about Gmod, even if your claim about not knowing what he was talking about is true, it doesn't eliminate the fact that you started yelling about it, actually, it just makes the Gmod rant more off-topic.