From my experience when I was playin orion and MOM, I think people whant to design race that are going to be powerful combinations. For example:
In orion: Subteranean + lithovore is very abusive
In MOM: Node mastery with nature mastery can quadruple mana received by nature node.
So players will always want to abuse the system and make the most powerful faction possible or make the faction that fit's best for their way of playing. The players never think on how the race integrate itself in the world.
My suggestions is that maybe races are prefixed and have abilities. New races can be added through modding. But players can add skill or abilities to their race which makes them a different variation of the same race. So that for example, 2 players could play the elves but one player call it the wood elves, while the other one the dark elves. At the base, they are all elves, and for city population, they might both be considered as elves.
Modifications could come From natural skills, government structure or anything else not genetic. But the genetic package will be the same for every player who select the same race.
In that case, you can make sure players can customize their faction and that the race they chose fit in the story of your world. It also prevent players from beign abusive: taking all the advantage they want and the disadvantage they don't care.
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An alternate but similar solution that could be interesting: One of my friend had a designed for an RPG game, a character creation system that was done by simply choosing background traits.
You had a series of background traits that you could choose for your character. Each of these background traits give bonus to various skills but players does not know which skill it increase.
So players makes their decision according to the story of their character and their intuition rather than focussing on the stats.
Results: Players get a more balanced character, they can make sure their character is focused in what they wanted without beign abusive and surprisingly, characters get some skills that they never tought of acquirering or using but could eventually be useful. It makes a combination of skills that players would not naturally choose.
So you could do something like this:
Players chose their genetic race ( HUman, elves, etc.)
Then player chose background story of their race: For example, they are nomad elves which got in contact though their travel with many crystals and they were living near water. So this could be details as:
elves - nomad - contact with crystal - coastal living.
This could lead to various racial ability: here is some random examples.
- Being nomad increased their hunting skills so they are better in combat and can find food more easily.
- Having contact with crystal give them magic affinity but reduced their fertility, so their growth rate is reduced.
- Living near the sea allow them to use an extra source of food and sea units gain experience faster.
I think that could be a very good way to make sure each player's race is unique by preventing rule abuse. I suggest that each trait gives
1 strong bonus, 1 weak bonus and 1 weak malus.
What do you think?