Like the Construction Set for the original Morrowind engine, OpenMW comes with its own editor, called OpenMW-CS, which allows the user to edit or create their own mods or original games.
OpenMW is a free, open source, and modern engine which re-implements and extends the 2002 Gamebryo engine for the open-world role-playing game The Elder Scrolls III: Morrowind. Performance and why isn’t my GPU being fully utilised?.What technologies does OpenMW/OpenMW-CS use?.