Bethesda Softworks is most famous for video games like Skyrim and Fallout 4, which are known for their vibrant modding communities. But the idea of shipping a level editor alongside an open-world game started with Skyrim's prequel's prequel: Morrowind.
Things were a bit rough around the edges back then, and strange things happened:
http://inuscreepystuff.blogspot.com/2010/09/jvk1166zesp.html...