Not too long after framing the question, I believe I've already come up with a good answer.

The question being: How does one bring about that sense of "purpose" that sets a subscription-worthy MMORPG apart from normal games?

The answer: Immersion.


In one last desperate lark to avoid doing the kind of mental heavy lifting that game development involves, I found myself picking up S.T.A.L.K.E.R.: Call of Pripyat and was catapulted into a thoroughly excellent example. I'll let the video do the talking as to just how immersive it feels, but let me outline some of the game design decisions that went into it:

• Minimal experience interruptions: S.T.A.L.K.E.R. has little to no instancing/load screens. For the most part, it feels like it's all one big flowing world.
• Life has no shortcuts, and neither does a lifelike game: In S.T.A.L.K.E.R. you're forced to walk wherever you want to go. There are shortcuts, but they're realistically framed: you can ask somebody to lead you somewhere for cash, the game fades out and in and game time has passed.
• A compelling world forces the player to pay attention: In S.T.A.L.K.E.R. charging blindly across a field to your next destination is likely to get you killed by hazardous "anomalies" and fauna. Consequently, the world feels appropriately dangerous to pay attention to.
• A realistic world goes on without you: a virtual "alife" mechanism populates S.T.A.L.K.E.R. with a lot of fauna that is sometimes engaged in life or death struggles regardless of the players' involvement.
• Only in games do you earn "points." A virtual world has more realistic accumulation: In S.T.A.L.K.E.R, there's a thoroughly believable economy that feels more like foraging for supplies instead of just hitting monsters until candy falls out. In fact, everything you recover from mobs they were using themselves, with nothing missing. (Except armor... perhaps the PC has an issue with seeing his enemies in the nude?) The personal advancement mechanic is completely hidden behind locating finding better equipment and upgrading it part by part with the assistance of engineers.
• Belief should not be suspended, but it should be reinforced: S.T.A.L.K.E.R. features compellingly realistic weather, a great ballistics model, realistic NPC behaviors (such as humans sitting down around a camp fire and one pulls out a guitar) and strange phenomena is portrayed in a realistic manner. These little touches all work together to preserve the illusion.

In short, S.T.A.L.K.E.R. weaves a rich, compelling tapestry of the senses that fully engages the player. It even makes sacrifices to the gameplay to preserve the integrity of this experience. I'm not saying it's perfect, it does have a few suspension of disbelief issues such as the choice to have NPCs lapse in and out of Russian or enemies with guns trying to shoot at you through walls sometimes, but it's hard to find a better example. (Perhaps The Path, which artfully bends reality to its whims.)

When you have a single player game with great immersion, that's cool. When you have a massively multiplayer game with great immersion, that's worth $15 a month. To pay such a fee, players expect to do more than just have the right to play a game, they expect to have a key to a world. If your world lacks immersion, it doesn't feel enough like a world to count. Here is where a sense of purpose becomes a factor.

Unfortunately, fostering immersion is hard. Doing differently in any one of the examples outlined above leaves something feeling off (and that's probably not a comprehensive list). Every little infraction tests a player's suspension of disbelief, and it doesn't take much for immersion to be lost.

• Star Trek Online and Champions Online lost all immersion with instancing, no attention to loot consistency, and thoroughly unrealistic environments and inhabitants. (Hrmph - I wonder if they'll humor a request for my lifetime subscription back.)
• Elder Scrolls IV: Oblivion and Fallout 3 were quite immersive, but then I reach to the end of the main plot and all context for the inhabitants was lost. The spell broken, the games' appeal was gone, even expansions seeming redundant.
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• Fort Zombie offers a pretty excellent feature list for immersion, with a scenario involving dynamically generated towns where you arrive to build a fort to survive a zombie apocolypse. However, it has a few big points that hurt it, such as crappy ragdoll physics.

Right now, I'm working in BYOND. You might think a 2D can't have immersion, but I would disagree. Look at Dwarf Fortress, for example. Even textual fiction can pull people in, after all. The imagination of the viewer is a powerful thing, one just needs to take care to operate with the proper frame of mind.