Wait... what? Wouldn't it make sense that the creator of a game engine would be the owner of said game engine? If not them then at least their publishers? In either case it wouldn't be the players. I agree with everything else you said, though: Using someone else's tools doesn't mean they own the rights to what you created. technically they do own, or zenimax may own it since they own bethesda, they stated that it was a completely new called the creation engine, but it is pretty clear that it is a modified or or based off the gamebryo engine, but there are multiple things needed to run the game, which they all license out from the respective companies that own them, and in doing so they include that anything related to skyrim, even though it may have to do with something bethesda dosent directly own, still is their property