These are three topics that I've considered already for the project. Composition was I term cause it sounds good, it's the composition of friendly forces, Opposition is the opponents of coarse, and affinity is a bit more complex involving my resource/trade system. These are all pretty much related and keyed into my concept of resources.
The Composition of the allies. Early on I'm going to limit it to three races. Maybe someday it will instead change to three factions or regions, but as is I'm making a simplified and cliched system of each race being its own faction and region. The summary of the three being...
Humans, native to the foothills and fields of the lowlands, and being industrious folk, they have greatly developed their affinity to the plains and to a lesser extent their quarries and mines. This gives them a greater affinity to plains resources than any others for mainly caster roles and a special plains based ranged class, and a lesser affinity to the more warrior based mountainous resources.
Elves, the people of the forests. Their affinity to the woodlands gives them unparalleled grasp of the woodland resources, mainly mastering the ranged and stealthy classes and receiving a bonus leather based warrior class. Their lesser mastery over growing plants in the clearings and lands near their forests gives them a lesser grasp over the lighter armored caster classes.
Dwarves, the people of the mountains, their homes being one with the forested mountains more often than not allowed them to master the mineral wealth of the mountains. This gives them the greatest understanding of the heavily armored warrior classes, recieving a special heavily armored caster class. They also have a lesser mastery of the forest resources, granting them some of the moderately armored ranged classes.
As it stands currently in a less flowery speech...
Humans, Primary Plains, Secondary Mineral
Elves, Primary Forested, Secondary Plains
Dwarves, Primary Mineral, Secondary Forested
Where Primary denotes a special class exclusive to the race, and secondary denotes an affinity to classes related to the resource as below.
Plains, Casters in light armor (denoted by cloth robes and plant/small critter based components)
Forests, Roguish and Ranged Types (Denoted by leather armor and ability to sneak through cover)
Mountains, Heavily armored Warrior types (Denoted by mineral based armors and weapons and toughness to live in the rough and hostile environs)
The opposition (the organized opposition anyways) is as followed.
Goblins, the bane of the Humans, they live in the same lands, however are quicker to pillage and steal the Human's resources and grow and dig up their own in their remote encampments or burrows. They also have mastered the art of casting and the occasional armored units.
Orcs, naturally camouflaged into the forests these stealthy but organized people are bloodthirsty and cunning. They have mastered the ranged and casting arts on level with the elves. However they quickly cut down forests and create their own clearings, stealing from and preying on travelers whenever possible.
Kobolds, the tricky stone in the heel of the Dwarves. While about as adept at magic as the dwarves, their skills reveal themselves in their traps and almost unbelievable organization whether under cover of trees or sneaking through tunnels. They sabotage and steal from the dwarves, appropriating and utilizing their resources and melting and reusing what doesn't fit their thinner frames.
Ta da, if you can't figure it out by now, its basically the same affinities for each race and their opponent. As of now, likely you can expect the same classes. Ideally however, the exclusive classes would be different for the 'monsters'
As usual, more to come...