This mod replaces Roundtable Hold with Majula from Dark Souls 2.
www.nexusmods.com
With this mod game should be playable from start to finish with all quests, every roundtable npc and event has been ported over, however report if you found any bugs with it.
I'd have to see them back to back, but I just played DS2 and the graphics look the same. Of course, I'm using a mod that improves the lighting, but From hasn't really pushed the graphics much in 10 years. Cool mod.