Peria Chronicles was a sandbox MMORPG that was a combination of that before it was canceled out of the blue during development. The biggest feature people were looking forward to enjoying was its full blown crafting system that allowed you to:
- Change and move NPCs, buildings, objects, and more
- Players can develop land, create structures and even create mini-games.
- Shape the world by crafting, building towns, maps, and writing their own quests and cutscenes.
All this was possible mainly because they allowed script editing, which gave players control over their creations.
It is probably how it would have felt if ESO was a modded Skyrim MMO…