MapleStory 2, welcome.

What part of VAST and OPEN do you not get? Here's a better example. Grand Theft Auto. It's vast, open, non linear. Maplestory is not vast and open.

Of course. I'm sure most would agree that MS is nothing like GTA's sandbox world. But on the other hand, I feel that Maplestory conceptually is more similar to an open world game, with its emphasis on exploration, the possibility of anyone and everyone entering maps, and the non-linearity of game progression. It might not fit the definition of a traditional, open world game, but I can see why myself and others wouldn't label it the opposite.