This will be a fairly abstracted strategy game, controlled by largely behind-the-scenes rolls and rules, where the players are semi-autonomous agents of a leader with significantly more power than they have.
Metamagic - Knowledge with any school is enough to counter magic from a similarly educated foe, but only Metamagic allows the identification and countering of spells from completely unknown schools. Direct metamagic spells tend to be weaker than comparably difficult spells from other schools.
Elementalism - Covers the five elements of earth, air, fire, water, and light.
Body Magic - Useful for healing and altering living beings.
Mind Magic - Includes illusions, among other things.
Soul Magic - Includes necromancy. Soul curses are best healed with soul magic. Intelligent creations require a soul.
Enchantment - Alongside its obvious uses, Enchantment allows a lesser, fake sort of pseudo-intelligence to be added into something, without playing with soul magic.
Conjuration - Creating anything corporeal purely from magic.
Divination - This is particularly useful for spying on distant places, communication, or countering spying attempts.
Time/Space(Advanced) - Studying this, the final school, is particularly dangerous. Anyone can destroy a city with a volcano spell, but what's the point of that, if it can instead by captured intact by teleporting an army directly to it?
There will be 10-12 provinces in the game. Each will have such stats as population, prosperity, mana generation, morale, tech, dominant race, intelligence data, and influence. The last will be a percentage of control. 40% INF will grant 40% of the seasonal tithes, 40% manpower, etc. A leader will try to keep a certain amount of control: An evil overlord will want near-complete domination, while a paladin would gladly share power with the clergy.
The players may attempt to gain more influence, either for themselves or the leader. This may not always be wise: If the church claims a mere 2% tithe, their wizard-loyal followers may well revolt if the players intervene harshly. On the other hand, letting them build up power unchecked may be equally unwise.
Even rebels may well agree to help defend the motherland against hostile invaders.
Every province has one dominant race, consisting of roughly 95% of the populace. Short of a systematic extermination, there will probably be some of every race somewhere in each province if the players wish to hire a non-standard race, say for a small mercenary group.
Humans:
Civilized Men - Many humans like living in big cities and forming empires. They get a bonus to population caps. They receive a malus to general combat ability.
Barbarians - Some humans like living in decentralized tribes. They get bonuses to general combat ability. They receive a malus to production and manufacturing (including arms and armor. This is standard to production and manufacturing).
Nomads - Whether merchants or travelers, some humans dislike living their lives in one place. They get a bonus to prosperity. They receive a malus to population caps.
Elfsies:
High Elves - Some elves live in big cities, and consider themselves superior to everything else. They get a bonus to mana generation. They receive a malus to production and manufacturing.
Wood Elves - Some elves live in big forests, and consider themselves superior to everything else. They get a bonus to mana generation. They receive a malus to prosperity.
Dark elves - Some elves kill each other in caves, and consider themselves superior to everything else. They get a bonus to subterfuge. They receive a malus to population caps.
Half Humans:
Halflings - A short race that eats too much. They get bonuses to population caps and prosperity. They receive maluses to general combat ability, production and manufacturing, and subterfuge.
Surface Dwarves - An industrious race of drunks. They get bonuses to combat ability and production and manufacturing. They receive maluses to population caps, mana generation, and tech spread.
Deep Dwarves - An industrious race of drunks that live deep underground. They get bonuses to production and manufacturing and defensive warfare. They receive maluses to prosperity, tech spread, and construction costs.
Others
Kobolds - A small race of strangely cute, yet weak, creatures. They get bonuses to defensive warfare and population caps. They receive maluses to mana generation, subterfuge, and troop experience.
Lizardmen - A race of bipedal, amphibious lizards. They get a bonus to naval strength and amphibious assaults. They receive a malus to production and manufacturing.
I'm blatantly stealing ideas from 10ebbor10's research structure. Researching a spell gives xp towards its overall school of magic. School and subset xp works differently than spell levels. [1.00] in a spell is akin to the first laboratory success in a controlled environment. Even a basic spell here uses a complex chant synched with elaborate gestures, and probably some sort of ritual. You might be able to conjure stones for construction just fine, if inefficiently, but using a [1.00] fireball in a fight is a bad idea. [2.00] is when a spell becomes practical, and is the "base" spell. [5.00] is the cap. Depending on the research focus, it could be reflexively cast while gagged and bound, be far more powerful, highly efficient, etc.
You could have several variants of each spell. Every offshoot starts from [2.00]. Obviously an Instant Thought Fireball is easier to research if you have already researched Blasting Fireball, Efficient Fireball, Instant Thought Flame Arrow, and Sticky Flame Arrow, with Elementalism at [3.00], but it won't give as much xp to Elementalism as an entirely new spell.
Note that while a spell cannot be cast below [1.00], a [1.98] spell is nearly as good as a [2.00] spell.
Having a school at a higher level is required for higher tier spells, and gives minor research, power, and efficiency bonuses to lower tier spells. You may research a spell to [1.00] for a spell one tier higher than the known school level, and levels [4.00] and [5.00] require the school to be one level higher than the spell tier.
Researching pure school knowledge is possible (And is advised for Metamagic, unless you know what counterspells you're trying specifically to learn).
Sharing is possible. Teaching just how to cast a spell is usually free. You may learn to cast a spell up to {3} this way. It's hard to research a spell if you're just given an activation phrase, and such knowledge will be {put in these brackets}. {Spells} may be researched at 1.5x the rate of other spells. Teaching the principles behind a spell can be done at a rate of 3x for one person, or 2x with multiple students. {Spells} learned may be cast at one tier lower than researched, but may fail. This allows players to teach tier 1 spells at {3} for any potential magically-capable subordinates, if Lady Zirae allows it. Sharing is fun! (For non-dark-elves.)
Players will be free to work together, either loyally or with the goal of wresting control from the leader, or splintering off on their own.
There will be more explanations before it starts.
Until then, feel free to reserve slots. I need votes on a leader and starting province.
For leaders, I need a name, agenda, focus of study, and weaknesses. This will determine how the NPC leader plays for most of the game. A paranoid evil overlord might horde his more powerful magic and harshly punish failure, but expand his realm nicely. A doddering old fool who wants only to study may freely give the players the results of his studies, and be easy to backstab, but be satisfied to let his single-province realm stagnate or grow on its own. Maybe he's insane and has banned the study of conjuration? Be careful not to get caught studying it.
For the starting province, describe it and I'll work from there. Is it an archipelago, difficult for outsiders to attack but with marginal mineral wealth? A large mountain range, full of ore but needing costly infrastructure to sustain the slowly-growing populace? Don't forget the dominant race.
Five player slots. IronyOwl has a free 24 hour reserve, if he wants it, since he won my last RTD.
EDIT: Early bronze age tech, no ruins of an earlier age. The wizard was the first in the province to somehow discover magic, and decided to teach it to a lucky few apprentices, for whatever reason. I blame this many civilized races on divine interference.