This latest version of SoB's Real Concussions uses a realistic fatigue system and a semi-realistic, heavily abstracted injury system at this stage.  Next iterations of the mod will include more specific injuries and game FX as one would expect from weapons, as well as vehicle crash injury effects and more.

Changes: 

Your character's gait will change with fatigue.  if you use all the mods at http://pastebin.com/ZdbBthB1, your experience will be interesting.

Latest version adds screen effects and randomization when injured.

BUGS:
low stamina characters like Trevor can run themselves to death fairly easily. 
Switching player models such as with a trainer can result in death due to default health values conflicting with player health.
ragdoll mod?  set a gate on it as suggested in the pastebin, or your character will fall over all the time


Optional files:

my choice of handling.meta as of 8 April 2016, as well as a no - UI version of the main script.


