I was just too impatient to play Chaos it would seem and spent twelve hours putting together my own take on a chaos race mod. It is not complete, at the moment missing all summoned demon types and the requisite spells (I hope to get to this). Also, most of the graphics are lifted from native, though the majority are reasonably appropriate. I expect Valandil will ultimately put together something rather different and his mod will supplant this one. This is meant to help Valandil with inspiration and maybe he can copy/paste parts of it. That plus it gives us something to play with in the mean time while he works on finishing his mod.
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Chaos Undivided in Mod thread- WH hordes of chaos.