I'm going to second Ashaman's opinion in that, while Designers may dream about these idyllic scenarios, they're just not realistic to implement.

Persistent & Dynamic Economy

Okay, now the title pretty much says it all, however, let's go in to more detail! Basically, you have NPCs, now, what if, wait for it, they ACTUALLY DID SOMETHING.... Yes! NPCs functioning as something else other than the wonderful conversation (heh..)! Enough of the jokes...

Example:
Gatherer NPC finds seeds, sells the seeds to the Farmer NPC, Farmer NPC plants and harvests them then sells them to Vendor NPC. Vendor NPC then sells to players or OTHER NPCs.

This idea is more geared towards a multiplayer environment, so as the player's actions can actually affect the economy. (Steal crops from the farmer, the farmer can't sell the crops, the farmer can't buy seeds from the gatherer, the farmer can't plant anymore seeds, and finally, the farmer can't sell the crops to the vendor for the vendor to sell, and so on...)

You could have a persistent simulated economy if it's the focus of the game - some sort of world simulation, but integrating it into an MMO for example isn't going to work because there isn't the scope for it to be a main feature. The economy of a farm is dependent on much more than a few crops.

If you have a field with the farmer's crops, a few lootable items to represent this and a player comes along and steals one, the farmer is losing a significant portion of his crop. In a couple of minutes of theft the farmer would be completely ruined.

If you have a large area, with dozens and dozens of items it'll encourage groups of players to come along and help themselves to free food, and the farmer is ruined simply because it's easier to take from the source.

Either, the effect a player has on the economy needs to be reduced (in which case, why not just simulate the economy without player interaction?) or the scale of the economy needs to be greatly scaled up: an example would be that Elwynn Forest in WoW would need to be just farmland in order to support an area the size of the original Stormwind.

You could add some simple price fluctuations into the market, but having a working economy would require an inordinate amount of work, for no real benefit.

Unified Massive Multiplayer Experience

This means that everyone is working towards the same MAIN goal, and are affected by changes in the world that one player causes. For example, I was just recently thinking of how awesome it would be to develop a Diablo fan-game. In this rendition, it would be a multiplayer 3D third-person hack-and-slash game with a dark gothic feel. Well, it would follow the story of Diablo II, but everyone would be involved, new and veteran players; however, this would be different from most MMOGs, as in the bosses are the only bosses and will not respawn magically from the pits of hell... The only thing to respawn would be your common enemies and the occasional unique mob, etc.. In effect, you would really be fighting to save Sanctuary from the three Prime Evils, which would be EXTREMELY difficult. By difficult, I mean several dozen level 99 characters still trying to struggle against their immense power. I mean, it would only make sense that the three Lords of Hell might be a little epic? Anyway, this is just an example (unless someone wants to help me develop it XD jk)

Anyone who's thought about making an MMO at any point, has dreamed about the Mythical "Real World" where what you do matters. But even something relatively simple - Large Bosses that do not respawn - is not realistic. Supposing you have these three primevals. Dozens of players work together over months, manage to kill one of them, it's a great accomplishment.

What happens to the players that missed out on the kill? People that were offline? What about players just joining the game now?

Someone joins the game a few weeks later, the second boss is already dead, everyone is working towards killing the third boss. They still have to level up to a position where they can help, by which point the last boss could be dead. When the last boss is dead, then what? Are you going to release an update with a new boss, and a new calamity? If you are, and will continue to do so whenever the next boss dies, then maybe you could get this to work.

Essentially, just by limiting the bosses you're limiting the endgame of your MMO, and that is always a bad thing.

Anyone who's thought about making an MMO at any point, has dreamed about the Mythical "Real World" where what you do matters. But even something relatively simple - Large Bosses that do not respawn - is not realistic. Supposing you have these three primevals. Dozens of players work together over months, manage to kill one of them, it's a great accomplishment.

What happens to the players that missed out on the kill? People that were offline? What about players just joining the game now?

Someone joins the game a few weeks later, the second boss is already dead, everyone is working towards killing the third boss. They still have to level up to a position where they can help, by which point the last boss could be dead. When the last boss is dead, then what? Are you going to release an update with a new boss, and a new calamity? If you are, and will continue to do so whenever the next boss dies, then maybe you could get this to work.

Essentially, just by limiting the bosses you're limiting the endgame of your MMO, and that is always a bad thing.

While this is true on a large scale I think that you could have a few unkillable bosses. Everquest had a boss that was intended to be unkillable, with enough time and progression of gear after years of expansions they finally managed to kill the boss. Stuff like this is legendary, people in the everquest communities talked about it for months and months. The three largest raiding guilds on Rallos Zek, including the one i was a member of, managed to kill the boss after hours of dying with over 250 players. He didn't even drop any items because he was intended to be unkillable.

http://en.wikipedia.org/wiki/EverQuest#Kerafyrm_-_The_Sleeper

Kerafyrm, "The Sleeper", is a dragon boss in the original The Sleeper's Tomb zone.
While sleeping, Kerafyrm is guarded by four ancient dragons (warders) in "The Sleeper's Tomb". When all four dragons are defeated by players and are dead at the same time, The Sleeper awakes, triggering a rampage of death. Kerafyrm travels through and into multiple zones from The Sleeper's Tomb to Skyshrine, killing every player and NPC in his path. This event is unique in EverQuest, as it only occurs once on each game server. Once The Sleeper awakes, neither he nor the original guardians will ever appear again on that server, unless the event is reset.
As of 05 April 2012, Kerafyrm remains asleep on both the Al'Kabor (Macintosh) server and the official Test Server.
Originally intended to be unkillable, SOE prevented a raid of several guilds on Rallos Zek server from potentially killing him, claiming the existence of a bug. SOE later apologized for interfering,[29] reset, and allowed the players to retry the encounter. Two days later, the same three guilds made a second attempt and after almost 4 hours, successfully killed the sleeper.[30][31] [32]
"Kerafyrm The Awakened" appears in the expansion Secrets of Faydwer as part of a raid event "Crystallos, Lair of the Awakened" in the instanced zone of "Crystallos".[/quote]

These are popular ideas that get posted very often on these forums, and so there might be a wealth of past discussions to discover. But nonetheless...

Persistent & Dynamic Economy

Gatherer NPC finds seeds, sells the seeds to the Farmer NPC, Farmer NPC plants and harvests them then sells them to Vendor NPC. Vendor NPC then sells to players or OTHER NPCs.

1. Hard to control, might not produce intended outcome.

I do research on "complex systems" such as economies and biological entities as a job. These systems, made up of thousands or even millions of moving parts are notoriously hard to control/predict. So much so that "complex systems" is a field of scientific research.

2. Takes too much time to make.

Related to my previous point. There are quite a large number of "simulations" you'll need to make in order to produce a piece of bread: weather, plant growth, harvesting, economics etc. Imagine doing so for weapons, armor, potions, magical trinkets etc.

3. Too little reward/gain.

If you game involves going into dungeons, why spend all these time making a complicated item shop? The time could be better spent making better dungeons. If players are playing your game for the dungeon aspects, they might not even notice the elaborate item shop mechanics. Also, it might be difficult to avoid inconveniencing the player (point 1). E.g. Running out of health potions, economy crashing etc.

Unified Massive Multiplayer Experience

this would be different from most MMOGs, as in the bosses are the only bosses and will not respawn magically from the pits of hell... The only thing to respawn would be your common enemies and the occasional unique mob, etc.. In effect, you would really be fighting to save Sanctuary from the three Prime Evils, which would be EXTREMELY difficult. By difficult, I mean several dozen level 99 characters still trying to struggle against their immense power.

This, too is a common idea. Like others have pointed out: what about new players joining the game? They missed all the old events that have taken place over the last few years. Instead of selling a game with 5 expansion packs of content, your game only has 1 expansion pack worth of content...you're throwing away old content. Furthermore, it runs into commercial problems: what do stores do with the 4 older packs? They can't sell it because the content is gone.

This, too is a common idea. Like others have pointed out: what about new players joining the game? They missed all the old events that have taken place over the last few years. Instead of selling a game with 5 expansion packs of content, your game only has 1 expansion pack worth of content...you're throwing away old content. Furthermore, it runs into commercial problems: what do stores do with the 4 older packs? They can't sell it because the content is gone.

This is a good point. Like I said in my previous post. You can't do this very much. I think you can get away with a few legendary bosses that are alive but essentially unkillable, and when i mean a few I mean maybe one every 5 expansions or so. It cannot however be the focal point of the game there must be plenty of other content. Maybe a good alternative is to make the bosses only respawn once every few days or even up to a month would probably be acceptable for a game with enough content. What you don't want to do is have a bunch of max level characters running around with nothing to kill... You have to keep them busy because once they get bored they're going to jump to another game.

I'll think about that and try to find a way to make it work where no content is missed.... I love a challenge.

1. If your "epic boss" take 1 year to beat, newcomers after a year will miss out on that content. If it takes 2-5 years to beat, people probably won't bother grinding 2-5 years.

2. High levels probably would have all the fun fighting the boss, while low levels die instantly and by the time they grind up the boss could be dead. Its easy to say "lets make it so low levels can participate!" but is there really a way of doing it? Low levels by definition will not be able to access the same content as high levels. They might "participate" by killing low level mobs but they will miss out on the boss fight or high level obstacles.

3. Can you imagine the lag 1000+ players in the same area fighting the "epic boss" will cause?