As exceptions to this rule, the enemy's response to player actions taken during stealth and combat alerts will always be high in one category and low in the other, or if the player stops eliminating guards then levels of both categories will reach level 2 or below after several missions. Levels of revenge categories can be decreased by completing a mission without doing anything that would increase the levels a common method of this being completing a mission while wearing the chicken hat or by doing a mission during the day without eliminating guards. Some common examples of this include soldiers wearing helmets if the player has been neutralizing them through headshots and wearing night-vision goggles if the player has been repeatedly caught infiltrating at night, multiple sorties in a row. When the level of a revenge category is increased it increases difficulty by adding better gear to a certain percentage of spawned AI. The revenge system is used in Metal Gear Solid V: The Phantom Pain as a game mechanic that adjusts difficulty based on various aspects of the player's methods of infiltrating outposts.
