Fallout combat Combat in " Fallout " and " Fallout 2 " is controlled by the participating character ' s statistics . When you select an enemy critter to attack , the game ' s rule system takes over . Basic combat rules . Combat generally begins with a surprise turn , where the initiator of combat takes an action and his target gets to respond . Regular combat rules follow . First off , the game determines who gets to go first . This depends on each character ' s sequence . The rule here is simple : higher sequence goes first . When it is your turn , and you choose to take an action , the game determines if you even have time in that turn to take your action . SPECIAL uses Action Points ( APs ) to work this out . Each action you can take in combat has a particular cost in APs . If your current number of remaining APs is equal to or greater than the cost of your action , you can do what you have in mind . A character ' s maximum APs are determined by Agility . Most attacks cost 5 APs by default , though with different weapons , modes of attacks and combinations of perk s , this can change . Movement costs one AP per hex moved . It is not enough to decide to attack . You actually have to connect before anything interesting happens . In essence , the target ' s chance of avoiding the attack is subtracted from your chance of successfully attacking . The resulting percentage is rolled against to determine whether you ' ve successfully hit . Your chance of successfully attacking is mostly due to your skill with whatever sort of weapon you ' re using , modified by attributes ( like Strength or Agility ) or perks . Your target ' s chance of avoiding the attack is mostly due to their Armor Class , which is determined by their Agility and the armor they are wearing . Additional bonuses or penalties to the attack can apply based on other conditions such as the range at which you attack or the lighting . Once an attack has been confirmed to be successful , damage must be determined . First , the raw damage is rolled . This is determined by the damage range of the weapon or hand to hand attack being used . Each weapon does more or less damage than any other . A slap from a 90 pound weakling hardly hurts at all , but a point blank shot from a combat shotgun is painful . For melee and hand to hand attacks , damage is modified by strength . Certain feats also can modify attack damage . Different types of ammunition can also have different effects on damage , depending on the Damage Modifier ( DM ) of the ammunition . Once the raw damage has been determined , the target ' s armor comes into play again . First , the armor ' s Damage Threshold ( DT ) is applied . This is a fixed number of points of damage that are directly subtracted from the attack ' s damage . Next , a percentage equal to the armor ' s damage resistance ( DR ) is removed from the remaining damage , eventually modified by the Damage Resistance Modifier ( DRM ) of an ammunition . Each armor has one Armor Class , but has different DTs and DRs for different types of damage . See Damage for information on damage types . The final damage caused by a ranged weapon can be computed by the following formula : ( final damage ) = ( ( raw damage * DM ) - DT ) - RoundDown ( ( DR + DRM ) * ( ( raw damage * DM ) - DT ) ) ) Where : If the player has the Living Anatomy perk , 5 HP of damage are added after everything else . " Note : The Fallout 1 engine does not implement the ammo modifiers , so in that game there is no difference between JHP and AP ammo . ( explanation thread ) " Taking too much damage will typically result in death . Characters have a derived statistic called hit points that represent how much damage they can take before they die . If you take damage equal to or greater than your hit points , you are dead , which is a shame . Attack modes . Some weapons have several different ways to attack aside from a single shot or a jab . First , every weapon ( except from burst - only weapons ) allows you to make an Aimed Shot ( provided you don ' t have the Fast Shot trait ) . Aimed shots allow you to aim for a particular part of a target ' s body . Aiming for limbs gives a chance to cripple the limb , which has several penalties . Aiming for the groin , head and especially eyes significantly increases the chance for a critical hit , but makes for a correspondingly more difficult shot . Many ranged weapons will allow you to make a Burst Shot . When you burst , you fire more bullets in less time . Different weapons will allow you to use more or less rounds in one burst , but the idea is generally the same : put more bullets in the air . The advantages of burst shots are that you can either hit one target for far more damage ( if multiple rounds hit and especially if several rounds achieve critical hits ) or to hit several targets at once as bursts fire in a cone . The downside is that bursts are more expensive in both ammunition and action points and may not necessarily be worth the expenditure . A further problem is that a burst shot may hit unintended target ( s ) , like your party members or neutral characters . Some melee weapons have different attack options ( jab , swing , etc ) and some , like the spear , have a throw option , which gives melee weapons a bit more range . Ranged combat . Ranged Combat is first determined by your Skill for the specific ranged weapons you are using . The Base to Hit ( BTH ) is the result of your Skill - 30 % . In addition you add 8 % or 16 % ( dependent on the maximum range of the weapon ) for each point of Perception - 2 , natural or modified by special perk s and traits like sharpshooter or Night Person to your BTH . Subtract 4 % for each hex distance between you and your target . You can also call an Aimed Shot , which also modifies your BTH according to the area you want to hit . In darkness also subtract additional 10 % if you are more than 4 hexes away from your target . Keep in mind if you miss there is a slight chance to hit another target . If you reach a BTH of 0 or below it is not possible to hit the target . Weapons also modify your BTH if you don ' t meet the minimum Strength needed to wield the weapon . For each point below the needed Strength subtract 20 % of the BTH . Some weapon - classes also affect your BTH . Shotguns for example raise your BTH by 20 % if you are > = 4 and even by 30 % if you are > = 5 hexes away from your target , while at the same time the damage done by the weapon is reduced . Sniper - Weapons like the hunting rifle can fire in the first 10 hexes away from your target with + 4 % to the BTH and without any distance modifiers . For Example : Your BTH is usually 55 % . While using the hunting rifle , you get initially + 4 % to your BTH . You are 8 hexes away , so your BTW is still 59 % . Beginning with the 11th hex distance between you and your target , each hex subtracts 4 % of your BTH as usual . In the example , instead of being 8 hexes away you are 12 hexes away , your BTH is reduced to 47 % . There are also special unique weapon modifiers like + 20 % BTH for the 9mm Mauser because it is " extremely accurate " . Criticals . If an attacker is lucky , he may find that his attack is particularly painful for the target , potentially causing crippled limbs , damaged eyesight or even instant death . These are Critical Hit s . When you make an attack , a derived statistic called critical chance is checked against to see if your attacking is critical . If it is , a random effect follows , which can be extra damage or more drastic outcomes . On the flipside , there are also critical failures . If you really fumble your attack ( characters with the Jinxed trait are notorious for this ) , something disastrous may occur . The most common result is attacking the wrong target ( for instance , you may be aiming at a mutant , but you will accidentally shoot your friend who is in between you and the mutant ) . Other possible results include weapon jams , dropping weapons , weapon destruction , causing damage to oneself ( by stabbing yourself in the foot or some such ) and other unfortunate outcomes .