GURPS - Basic Set 3r..

Opportunity FireA character with a thrown or missileweapon may stand still, watching a specifiedarea, and fire as soon as a target presentsitself. This is opportunity fire.To take opportunity fire, you mustchoose the Step and Wait maneuver. Yourcharacter is now staying still, facing thedirection you choose and watching for atarget in a specified area. If a targetappears, you must fire (or throw) yourweapon (but see below). This takes placeimmediately. You may do nothing elsethat turn. If no target appears, you simplywasted that turn.All of the area to be "covered" must bewithin your arc of vision (see p. 115). Thelarger the area you have to watch, thegreater the penalty when you fire: One hexbeing watched: -2 Two hexes being watched:-4 Three or four hexes being watched: -5Five or six hexes being watched: -6 Seven toten hexes being watched: -7 More than tenhexes being watched: -8 You may alsospecify a single straight line, and say thatyou will fire at the first target that crossesthat line. The penalty for this kind ofopportunity fire is -5. All normal modifiersapply to opportunity fire.If you want to keep your foes fromknowing where you are planning to fire,just tell the GM secretly.If two or more people are taking opportunityfire at the same target, they all fire ateffectively the same time.When you announce that you will takeopportunity fire, you must fire at the firstenemy that appears in the designated area!The GM should make sure that playerscarefully specify the area they are watchingfor opportunity fire.Opportunity shots are automaticallysnap shots, regardless of your effectiveskill; the -4 penalty is built into the abovenumbers. Exception: if you are watching asingle hex, you can Aim while you wait for atarget. This will give you the normalaiming bonus when you finally fire. Eachturn you wait for a target counts as a turnof aiming. However, if you are watchingmore than one hex. you cannot get an aimingbonus at all.If you want to specify that you are notfiring automatically, you may do so. When atarget appears, the GM makes yourVision roll for you and tells you whetheryou think it's friend or foe. You are at a -2to your shot because of the time you willspend deciding.Characters who are kneeling or lying down are not in the way unless you, too, are attheir level.Because hitting the wrong target is a matter of pure chance, your attack roll againsteach character is the same: a flat 9 - or the number you would have had to roll to hitthem on purpose, whichever is worse.Roll first for the target closest to you. If you miss (or if the target dodges) roll for thenext target, and so on. Keep rolling until you hit, or your attack is blocked or parried, or yourun out of targets. If your attack went along a line between two occupied hexes, rollrandomly to see which one you check first.Anyone (friend or foe) gets the same defense against this attack that he would havehad if it had been directed against him intentionally.Head only: -5 to hit.Behind light cover: -2 to hit.Lying prone, minimum cover,head up: -5 to hit.Head and shoulders exposed:-4 to hit.Behind someone else: -4 tohit. see above.Lying prone, minimum cover,head down: -7 to hit.Body half exposed: -3 to hit.Lying prone without cover:-4 to hit.Crouching or kneeling, nocover: -2 to hitCover and ConcealmentIf you hide behind something, you will be a harder target for ranged weapons. Thebetter the cover, the harder you will be to hit: anyone shooting at you must target anexposed part of your body. Some examples:Head only: -5 to hitHead and shoulders exposed (e.g.. firing a weapon from a trench): -4 to hit.Body half exposed (e.g.. firing from behind a tree, or standing behind a smallembankment): -3 to hit.Behind light cover (e.g.. a screen of bushes): -2 to hit.Behind someone else: -4 for each human-sized figure in the way. See FiringThrough an Occupied Hex. p. 117.You can also make yourself a harder target, even without cover, by crouching orlying down:Lying prone without cover: -4 to hit.Prone behind minimum cover (e.g.. a body), head up to observe: -5 to hit.Prone behind minimum cover, keeping head down: -7 to hit.Crouching or kneeling without cover: -2 to hit.Based on these examples. GMs can interpolate a reasonable penalty for any exoticmethod of concealment the players may devise.