hmm im not sure, but maybe you should also add
gray in the black and white story.
though, yes, it is the default placement for anyone.
but some people, like me would want to stay true neutral for some reason.
they could gain light and dark points by half of what the specialist would have. and the more they get to mix the black and white in an even balance
state, they get better deals for their equipment's stats.
if you have toomuch black, +STR and -AGI or viseversa.
so if you are in the middle, you suffer no loss in equipment stats.
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by the way, maybe in some point, the affinity of the players would
affect their skills in realistic ways.
Fallen Crusaders/Paladins (dark affinity)
should have their GrandCross be called The BlightCross
and it's on shadow element.
While True Paladins (Light) would have special added effects
when using THEIR holy skills.
Priests become DarkPriests and have their Heal in dark affinity
so they damage instead of heal. (heals people in Shadow Armor)
Their Magnus Exorsisimus becomes Magnus Necrosis...
Their Resurrection Would Resurrect you, but in a Zombie state, etc.
Geez, I dont know, :D i'm just throwing in ideas here hoping it would trigger a better one, or something.
edit:
Oh, to also give a good reason to chose sides,
maybe we could impliment a learnable skill (quest skill)
that has relevance to the character's affinity.