Here is something I wrote copied and pasted from another thread:
Here is a breakdown of Midnight vs. Standard D&D (Greyhawk)
Izrador, The Shadow of the North
The source of all the major changes. 8,000 years ago, there was a war in the heavens. The dark god, Izrador was defeated and expelled from heaven. However, as he fell to the mortal world, his final act of vengence was to sever the world's ties to the planes.
The Wars
Izrador's wounded essense descended upon the world and immediatly sought shelter in the frozen wastes of the north. After thousands of years, Izrador regained some of his former power and sent his armies of Orcs south into the human, elven, and dwarven lands. After a horrible battle, the Shadow was fought back. Defeated, Izrador's minions withdrew to lick their wounds.
Centuries later, the Shadow again poured forth from the frozen north, and agian was defeated. However, many secretly turned to the worship of Izrador and it was their treachery that fueled a third war.
100 years before the present day, the third war came to a bloody end. The forces of humankind lay defeated. Civilization crumbled. The elves retreated to the forests, the dwarves to the mountians. Both of which became the front lines of a bloody war that still rages. The majority of the halfling race was enslaved. The humans that survived fell under an unholy oppression.
Orcs, goblinoids, giants etc led by the worshippers of Izrador called the legates, have gained control of most of the world.
Rare Magic
Magic is the province of Izrador and his minions. Divine magic functions only for those who worship the Shadow as the other gods haven't been able to contact their worshippers since Izrador fell.
Arcane magic is still practiced by both those who oppose Izrador and his minions. However, its practice is punishable by death for those not loyal to the Shadow. To make things worse, the legates have demonic companions (Asteraxes aka. Sniffers) who can smell the use of magic for a mile and hunt those who would use it.
A major change from typical D&D is Midnight's magic system. All classes can learn to cast spells. Only a feat is required and casting is based on character level. There is a class that specializes in casting called the Channeler.
The spellcasting system works like this:
Feat: Magecraft - This feat is the intro feat and requires you to pick a path (Hermetic, Spiritual, or Charismatic). You gain the use of one 0 level spell.
Feat: Spellcasting - This feat allows the spellcaster to gain access to one school of magic. Characters can then learn spells from that school and cast them. Each time this feat is taken, you gain access to a new school. (Some of the schools are slightly different than normal D&D. For example, Evocation is broken into Lesser Evocationa and Greater Evocation.)
Casting Spells - Depending on certain factors, all spellcasters have Spell Energy. when you cast a spell, you deplete a number of Spell Energy Points equel to the level of the spell. Once you run out, you can continue to cast spells, but the cost is taken from your Constitution score. You may only cast spells whoes level is equel to half your character level.
Classes
You may play Fighters, Barbarians, and Rogues as normal.
Defender - This is a sort of monk without supernatural powers.
Wildlander - A ranger like class without spellcasting abilities.
Channeler - This class gives several bonuses to spellcasting.
Playable Races
Humans (3 subtypes - Erenlander, Sarcosan, and Dorn)
Snow Elves
Jungle Elves
Aquatic Elves
Halflings
Elflings (Elf/Halfling)
Gnomes
Dwarrow (Gnome/Dwarf)
Dwarf
Dworg (Dwarf/Orc)
Orc
Heroic Paths
Every PC selects a Heroic Path at first level. These Paths are sets of special abilities gained at each level that proceed along a theme. This makes up for the lack of magical items lacking in Midnight and gives the characters an heroic edge against the Shadow. Examples include the Giantblooded who are size Large, the Ironborn gain additional hit points and eventually damage reduction, the Shadowwalker who can see in the dark and summon shadows, the Dragonblooded who are powerful spellcasters etc.
Planar Connections
The setting of Midnight is completely cut off from other planes. Teleportation doesn't work. Summoning spells summon creatures from elsewhere in the world. Also, dead people can't get to either heaven or hell and often rise as the Fell. The Fell are undead creatures who retain their intelligence but are driven by an unholy hunger for flesh. Without flesh, they eventually become zombies and then may further degenerate into skeletons.
Economy and Culture
Since the wars, civilization has been crushed and scattered. Gold coins are worthless in most parts of Eredane. A loaf of bread however, may buy you a bed to sleep in for a day. Weapons are illegal. Literacy is illegal.
One of the more unique aspects of Midnight is that trade uses a barter system. All characters start with 4 ranks in either a craft or profession. You need to use these skills to get by.
In general, Midnight campaigns focus more on the character himself and not on his magical items or spell lists.
Questions??
But, it is very good. They have a Players companion as well as a mega adventure. They are bringing out Minions next month which is a little monster book, little NPC book and a little resource all rolled into one. 
