Locations (arms, legs, torso, head) can be crippled by certain effects and attacks. Any attack which inflicts 1/4 or more of the player's total hits in damage (i.e. 8+ for a normal 30-hit human) automatically cripples the location it strikes.
A crippled limb cannot be used to attack or block in combat and cannot bear the character's weight. If a character's torso is crippled, they are unable to move faster than half speed or engage in combat until healed. If their head is crippled, they become unconscious for 5 minutes, and thereafter may not engage in combat and suffer a -1 Intelligence penalty until healed.
Cripple is a status effect.