What he's describing is nothing like that. He means stuff like creating new civics - tedious, since you have to modify python and xml to make it beautiful, and it can get confusing. If you could just use a modifier that shows all the screens and you can modify them, it would be great. Like, click on the tech tree icon and you can add/delete new techs, click on the civics icon and you can add/delete new civics and civic options, and move the civic windows around, and stuff like that. World builder just lets you place items, change the appearance of the map, and modify diplomacy. What he is suggesting would be taking that a step further - allowing you to modify certain game mechanics without having to enter xml, python, or the cursed Computer-Type Rascist SDK.