What are critical hits? How do they work? Typically there is some percent chance to crit which causes an attack to deal some percentage extra damage. Commons values are in the ranges 1-30% chance to crit and 35-300% extra damage. In an RPG this works as you’d expect. For each swing of the sword you roll the magic random number generator dice and check for a crit1.

Team Fortress 2 has an interesting crit system2. Guns have a 2% base chance to crit which temporarily increases as the player deals damage. Slow firing guns (shotgun) check for crit with each shot similar to an RPG sword. Rapid fire guns (uzi) check once per second and crit in two second bursts.