The Chosen

First I would have all the features described elsewhere in my rantings. As for races, I would prefer the following:

Human
If stats are, for the moment, Super-Great-Good-OK-Fair-Poor-Awful, then Humans should have a max of Great on all their stats (strength, intelligence, wisdom, dexterity, constitution, charisma). Their resistance and natural armor should be average. They should have no class restrictions. If levelling is measured, for the moment, in units of 50, then humans should take 800xp to level.
Elf
Elves should have a min of OK and max of Super on intelligence and dexterity, and a max of OK on constitution Other stats max at great. They should level every 1200xp. They should have some very minor magical skill (one first level spell) and cannot be charmed.
Half-elf
Half-elven should have a max of good on constitution, and a max of super on dexterity. Other stats max at great. They should suffer all the racial biases of elves AND humans, no inherent magic skill, and cannot be charmed. They should level around 1000xp.
Drow
Intelligence, dexterity, and wisdom max at super. Constitution maxes at fair. Strength and charisma max at good. Inherent magical tendencies should include 3-4 low level spells. Suffer extreme prejudice from all other PC races. Level at 1500xp.
Dwarf
Dwarves have a min constitution of great and a max of super. Intelligence maxes at good. All other stats max at great. They are highly resistant to magic and blunt attacks. HIGHLY. They level around 1200xp.
Halfling
Halflings have a min dexterity of great and a max of super. They also get an really big AC bonus for any creatures bigger than themselves. Other stats max at great. Level at 1100xp.
Half-Orc
Half-orcs have a max of OK on charisma and wisdom, a max of good on dexterity and intelligence, and a max of great on strength and consitution. They are meant for players seeking a challenge, suffer lots of racial bias from all groups, and level at 800xp.
Gnome
Gnomes max at super on intelligence, and all other attributes max at great. They have no inherent magic, and they level at 1000xp.
Pixie
Pixies min at super on intelligence and dexterity; they max at great on wisdom and charisma, and good on strength and constitution. They can always fly (no spell needed). They have several inherent magical abilities (5-6 low level spells), and they level ay 1500xp.

The inherent spells listed above should only require 2-3 mana point or so, as opposed to spells learned as a spellcaster. Hence I recommend the spells no be the same as those used by spellcasters. In fact, how spells are divided up is a critical aspect of character development.

The classes are divided into cleric, fighter, thief, mage. (I would prefer the harder to program but more flexible and rewarding classless system, though)Those choosing a race with inherent spells get those no matter what class they choose. Again, the spells for each race can only be had by selecting that race, and are not on the class skill list of either mage or cleric.

To further add flavor to character development, there will be 5-6 deities. Each of these will hold power of certain things, like Life&Death, War, Magic, Nature, Mercy&Judgement. These will have no set "alignment". They merely promote their sphere. Their followers may be of any alignment, but it is a gamble when you try to guess how to please a god. By following a deity you recieve certain skills/spells only availabe to servants of that deity. There are different skills for spellcasters and nonspellcasters. Here is an example/rough sketch:

Bhaal
The deity who oversees birth and death, who gives life and takes it away. He is revered and feared as he sends out his servants the Mornok, spirit-beings who deliver and take away souls from the mortal world. His supplicants hope to live longer by gaining his favor, but such a reward is hardly assured even for the most loyal followers. Bhaal is allied Thoram and Gentha and opposes Naulya.

Special skills include harmful and restorative spells (that hurt or harm the life force of an individual, including energy drain and level restore), and also the channeling/summoning of spirits. Bhaal only accepts clerics and thieves as followers. Thieves gain slightly different skills, most involving the art of killing and more or less resemble an assassin class.

Furos
The deity of conflict and war, Furos is revered by warriors and beseeched by commanders on the eve of battle. He tends to help those who prove themselves worthy, and those who enter a fight without so much as lip service to him are risking more than defeat. Furos is allied with Thoram, and squabbles with Naulya.

In general special skills include spells like "battlemind" and "spirit hammer", things which aid one in combat (but nothing to do with armor or protection). Furos only accepts fighters, thieves, and clerics as followers.

Naulya
The deity that opens the paths of the arcane to mortals, she is the goddess of magic. Naulya's favor is sought by mages creating spells, potions, and the like. The difference between mages and clerics is that mages can indeed create new magics of their own design, rather than accepting only that given by a god. Thus the mages class has so much variety in the number of spells to choose from, including those which unlock the secrets of life and death. It is for this reason Bhaal is opposed to Naulya. As human mages meddeled in necromantic spells they found ways to tap into the flow of life/death energy beyond the mortal realm, creating the Undead. In selfish experiments meant to cheat death, the secrets of creating skeletons and zombies were made. Unsatisfied with the results the mages pushed deeper, resulting in wights, wraiths, and other ethereal forms. Finally the mages stumbled across the formulae for vampires, liches, and skeletal warriors, and their quest for immortality became a blight on the mortal world. Ghosts are not included here as they are the spirits properly allowed by Bhaal to wander the mortal realms, and only these may be channeled/summoned by his servants.
Naulya grants extra mana per level to her servants, as well as mana spells found nowhere else, including spells involving divination, lore, and the hidden. They also get the ability to detect magic as an inherent spell. Naulya only accepts mages, clerics, and thieves as followers. Thieves recieve slightly different skills than the spellcasters, and resemble the class generally known as Bard.
Gentha
The deity of the wilderness and the representative of the natural creatures of the mortal realm, Gentha is the goddess of nature. She has a strong affinity for Bhaal, but doesn't share his bitterness toward Naulya. She has quarreled often with Furos, and has been known to challenge Thoram.

Gentha's servants recieve many spells pertaining to plants, animals, and nature (finding them, identifying them, etc). They also gain some control over the weather. Gentha only accepts clerics, fighters, and thieves as followers. Her clerics are this worlds equivalent of druids, and her non-spellcasters are eerily similar to rangers.

Thoram
The deity of justice and mercy, Thoram has the burdensome duty of supporting the cornerstones of civilization. While there are some universal absolutes in morality, there is often quite a bit of local (and circumstantial) variation. While generally seen as a goodly force, he must support those who are on the side of law. Yet many who thought him blind to their hypocracy have found themselves begging for his mercy, only to recieve his justice.

The followers of Thoram are critical in assessing the merits of what is just in their own realms, and much of Thoram's burden is passed on to them, along with much of his power. It is a serious and grave duty, requiring the ability to see past emotion to assess the merits of each case, yet not be so hardened as to forget the purpose of the heart. Fair and impartial is the watchword, and those who fail the standard are stripped of their powers, at the least. Thoram only accepts clerics and fighters as followers. Oddly, his fighters resemble the class known as paladin.

As far as the above deities go, only clerics MUST choose one to follow. The benefits are balanced by the fact that you are at that powers beck'and'call, and it adds +150xp to level. While each deity is presented in pure form here, good roleplay would allow for cults or factions to worship a certain aspect of each deity, such as an assassin version of Bhaal or a musical, magical, lore-laden and elven-esque version of either Naulya or Gentha. In fact, you can roleplay as following more than one god, but in game mechanics you can only pick one.

So. Let's assume all my ideas are in place. What is the plot? Well, I thought characters would start in a typical MUD world, except that it would have been dead for a long time. Everything crumbling, a few bleached bones or rusty swords here and their. No life bigger than rats, giant rats, spiders, snakes, crows, etc. No matter where you go everything is in ruins. The lousy starting equip would be explained in this context-rusty armor and sword, really old everything. But there would be hints of how things used to be. Royal crests, faded signs lying on the ground. Sacked and burned castles. Abandoned farms and temples. Thus newbies get basic equip and xp from the MOBs and practice looking, moving, etc. There would be a special room near start (recall) where players would feel something just beyond their senses. When they reach level 5 they can then see what it is--shimmering portals. Each portal takes them across time and space-to when the kingdom first started--to it's hey day--to the day's just before it's fall. Each map is the same in layout but of course different in content since you are in different eras. It is like a mystery-what happened to these people? What devastated this world? The portal room would be active in all worlds, but only PCs can see it. And oddly enough, every time a PC is killed, Bhaal determines it is not their time and sends them back....hmm, quite a mystery. And even after the first 3 portals open, there are others you can't quite see yet, for later levels. The question is, why have these mortal been Chosen? Of course, the answer is the same in all MUDs but here it is an interesting part of the story--they have been selected as worthy to quest to be an immortal.

What about clans? And shadowbeings? And multiclassing?

Clans are not necessarily referred to as clans, but as affiliations. These can be true clans, cults, citizenship/military service, adventuring companies, etc. The affiliation also gives special bonuses and skills, just like race and religion. There are 3 permanent affiliations officially headed on NPCs but run by their PC-designated righthand persons. These include some type of roleplay military, a thieve's/mercenary company, and the dark secretive Shadow Cult.

Each affiliation has some permanent descriptive change to its members. No matter what equipment they wear or how the write their 'descrip', it is a permanent part of them. And it confers certain properties. For the military it is a uniform, for the thieve's it is a stylized brand, and for the cult it is a new body. In the case of the shadow cult, members actually gain a permanent ethereal form throught the dark magics of their leaders. Other affiliations created by players are also welcome. Because of the skills gained and support given through affiliation, joining costs 100-150xp.

Multiclassing is allowed but remember your deity. Followers of Bhaal can't multi-class to mage. And of course there are xp penalties for multi-classing.