no is not "open world " is largte environment but its not an open world where you can go anywhere for the whole lenght of the game its divided in levels , check the editor ...
save it as a .ma and make sure they open it with the open options and check ignore version. should work for just a model. I've used it on complex rigs, and it worked ok.
All I know is this. I'm opening the cage in the opening and I'm putting on the apprentice mage robes. I don't care if there's better armour. Robes all the way!