The Alien Hand (-4, -6, -8)

Characters with Alien Hand have a brain injury that causes their nondominant arm and hand to apparently act of its own accord. This cannot be repaired with available medical technology and, because it is a brain condition, effects any replacement arms that the character may have, including cyberarms.
For the -4 point version of this Flaw, a character's nondominant hand experiences instinctual avoidance syndrome and will pull away from anything. A character with this flaw must make a Willpower (4) test to touch anything with his nondominant hand and a Willpower (6) test to hold anything in that hand. In all other ways, the hand acts normally.
For the -6 point version of this Flaw, the character maintains partial control of the nondominant hand but it may randomly grasp for things at the GM's discretion and the character may have to make a Willpower (5) test to release objects held in that hand.
For the -8 point version of this Flaw the Alien Hand will, at the GM's discretion, act at fully of its "own" accord and will often interfere with the character's intended actions. A character with this level of Alien Hand will often find his nondominant hand undoing tasks accomplished with his dominant hand. For example, a right-hand dominant character may load his weapon with his right hand only to have his left hand unload the same weapon before he can fire. Performing any voluntary action with this level of Alien Hand requires a Willpower (8) test as does preventing it from performing an action.

In combat, the Alien Hand is considered to have its own initiative equal to the character's initiative and always acts after the character.

I like it. I think I will be introducing this to my players when next we meet.

i've got these evil hand issues!

What happens if the player cuts the hand off and replaces it with a chainsaw?

You suddenly have an arm with a chainsaw swinging around that you can only control half the time and get the nickname "Stumpy" after it removes your other arm, both legs, and then your head.

Or you end up getting sucked back in Medieval Times and fghting a horde of Deadites, lead by your undead evil twin. Mostly because you couldn't remember the last word in Klaatu Verata Nictu.

What was the original ending?

...when Ash awakened and came out of the cave, he discovered he was in a post apocalyptic England. This occurred after he drank a one too many drops of the potion he was given which caused him to oversleep by a century.

That's funny. I like it!