EQ1 had the Lost Dungeons of Norrath, which changed every time you played (well, actually, they selected from a few). If someone just played by hanging out in the North Ro Wayfarer camp, grabbing a group, and doing LDoNs over and over — as many people did — were they playing an MMO?

You’re shifting the reality of the game to the player’s perspective, rather than the reality of the world as it’s been designed. The fact that (in your example) you’re not availing yourself of the rest of the world doesn’t mean it ceases to exist as a MMO. If I’m playing cards in chat with my group mates, EQ doesn’t become a card game. My personal experience is that EQ–for the moment, and for a limited scope–facilitates a card game, but it’s a localized experience. Meanwhile the rest of the world continues to exist as designed.

I think what really squashes the idea of Diablo being an MMO is the first “M”–Massive. You can only have, what?, 8 players in any given Diablo instance? (it’s been a long time, I forget) That’s not massive by any definition. Yes you can have a ton of players in the lobby, but the lobby isn’t the game. The lobby is chat. It’s completely disconnected from the actual game. The fact that you can play Diablo as a single-player game with no online connectivity attests to the lobby’s small importance to the actual game.

D2 had persistent characters, levels, loot, group and solo play, quests and all that — and it even had a community. About the only thing it doesn’t have is the ability to customize your own avatar — and if we choose that as the tipping point, than WoW and EQ1 are just barely MMOs (and CoX becomes the most MMO-ish game ever!)

All characters look pretty much alike in their armor. You recognize someone by the name hanging over their head. Diablo 2 has that.

D2 is an MMO.

The big thing that keeps Diablo from being a MMO in the classic sense of the term is not just its lack of persistence, but also the lack of a persistent community within a single instance (shard/realm/server) of the world. The lobby is somewhat persistent, but it isn’t tied so much to your avatar as to your account.

Diablo also lacks a virtual geography. You aren’t so much in the world of Diablo as you are in tightly controlled enclaves of the world. Furthermore, those settings change their layout every time you play.

All this is in Diablo 2. I’ll admit that not having non-instanced areas is a big drawback. Aaron’s point about character identification is valid–Diablo had no personalization past character name–but plenty of mainstream MMOs encourage you to treat your dude as a playing piece instead of a little you.

Is it worth noting that multiplayer play in D2 wasn’t very good? There wasn’t much synergy between characters, and no enemies that actually required cooperation to defeat. It was common to get a bunch of people in the world so enemies would be tougher and give more XP, but you’d all play in different places to not step on each other’s toes. It could be that this experience–playing solo in the same game as inarticulate strangers–causes me to think D2 is more MMOey than most people do. :)

You see in the newspaper someone selling QVC Bucks for cash. QVC has now, by Tipa’s First Rule of MMO Categorization, become an MMO.

The other way you can tell if something is an MMO is if it’s isomorphic with an MMO.

Sure, shopping may seem like a funny idea for an MMO. But the MMO world is being pretty constrained by having to be similar to old MUDs. Future MUD-derived MMOs risk just being parodies of MMOs, a line Vanguard is edging. (”Your game has ten races? We have fifty! Your game has six classes? We have ninety-two! Your game world is the size of Rhode Island? Ours is the size of Canada and Greenland put together! Your game runs on an old Pentium 2? Ours takes a Cray! Our mountains are twice as high and our oceans twice as deep! So there! Our game crushes your puny game!”)

I have often wondered about the apparently thriving RMT black market for Diablo 2. I suppose it is a sign of success, but still.

When wondering if a game is or is not an MMO, I look to the gold farmers.