Virus93
isnt it just MASSIVE MULITIPLAYER ONLINE
Depends on how it's used.
In MMORPG, for example, is massively multiplayer.
Massively is an adverb describing the quantity of multiplayer, which is in turn an adjective.
In MMO by itself, multiplayer is a noun (as it doesn't describe RPG) and therefore "massive" is used as an adjective, instead of an adverb.
So if you have MMO+anything, it's MASSIVELY.
MMO by itself should just be MASSIVE. (So you were correct)
Though you generally don't see it used by itself.