Risk is a combat system mechanic implemented in Vagrant Story (2000) as a means of balance. The game's primary combat mechanic simply involves pressing a button on the controller in rhythm, and so long as the player maintains that rhythm, they are able to continue to chain their attack for a theoretically endless amount of damage. The player can focus on specific limbs or the enemy in general while attacking to maximize damage output.
In order to prevent players from simply chain-attacking every enemy to death (thereby making it a dull and repetitive game), the Risk gauge increases with each hit so that the player is encouraged to stop attacking after a couple of hits in order to keep their Risk low. This, in turn, gave the enemies an opportunity to attack the player which ultimately balanced the combat.
The effect of high Risk is twofold: It decreases the likelihood of a successful attack but it increases the likelihood of a critical hit. A player could certainly chain 50 hits on a boss, but as soon as the player messes up and breaks the chain they will have full Risk and the chances of connecting another hit before the boss retaliates is slim to none. As a result, the system encourages the player to never chain longer than necessary -- usually about 4-6 hits per chain. The player should intentionally break the chain and start over again to keep their Risk as low as possible while dealing as much damage as possible.
The Risk system's limb-targeting mechanic is similar to SD Snatcher (1990), the VATS system of Fallout 3 (2008), and Last Rebellion (2010), while the pausable real-time aspect of the system is similar to Parasite Eve (1998), Star Wars: Knights of the Old Republic (2003), Final Fantasy XII (2006), and Fallout 3 (2008).