Ok, so no one seems to understand this concept anywhere I've looked for it.
What I am looking for is an MMORPG that you can play ONLINE as an MMO or OFFLINE as a standard RPG.
Playing offline would let you get exp, items, skills, etc that you can still use in your online character. So both parts would have a shared character.
The closest I have found is .hack//frägment, which was only in Japan and no longer in service. I can link the wiki article for the game if it helps get my idea across.