Inspired partly by the Elongated Limbs rule from Rogue Trader RPG, and partly by John Blanche's serpent man thing from the 5th Ed. rulebook, I came up with this -
Twisted Limbs - Possessed of limbs with more joints than any clean-blooded human would have, the character is disturbingly nimble and flexible. They have the Subdue and Scale Terrain abilities, but have -20 Toughness for their limbs.
Does that seem good?
I like it. Good and flavourful, marks someone out as a mutant without giving him superpowers.
i agrea its to the point with not to meny extra rules good idear