Hit Scan

In some early videogames, the game engine did not have enough computational power to actually keep track of all moving projectiles (like the bullets fired from the player's gun), let alone incorporate realistic physical factors like atmospheric friction or gravity.

In some games, this was mediated by placing a limit of One Bullet At a Time. In others, developers chose a Hitscan weapon.

Hitscan weapons do not actually fire anything; instead, when the player pulls the trigger, the weapon traces a line in front of the player and instantly hits whatever the line intersects with first. This differs from a projectile weapon, whose bullets are independent data objects with a known position and speed (be it fast or slow) that the game actively tracks and checks against potential collisions. A hitscan can be useful in situations where the projectile is moving so fast that it would be difficult to track, such as with realistic lasers and bullets across short distances.

It should be noted that hitscans can overlap with projectile tracking: In some cases, the actual attack is hitscan, but the game will still animate a fake projectile moving from point A to B. This allows Every Bullet Is a Tracer to play together with hitscan weapons. This can become particularly obvious if the tracer is too slow or the game supports Bullet Time, as you can see enemies recoil before the "bullet" strikes them.

In older shooters this was used for any bullet-based weapon, on the assumption that bullets moved too fast to evade or dodge anyway, and also to balance them against more powerful projectile-based weapons, which were trickier to aim. For example, in Doom, the pistol, shotguns and chaingun were hitscan, while the plasma rifle, rocket launcher and BFG fired projectiles. Hitscan enemies are often Goddamn Bats, since the player is more or less incapable of dodging their attacks.

Note that lacking or averting this trope does not necessarily mean that bullet projectiles behave realistically; for example, the game may still destroy projectiles once they reach an Arbitrary Maximum Range rather than having them follow a ballistic arc until they hit something. Gravity is also often not applied to projectiles.

Paradoxically, while bullets are often implemented as a hitscan, energy weapons are usually portrayed as Painfully Slow Frickin' Laser Beams. See also Homing Boulders

Examples of Hit Scan include:

Wolfenstein 3D. Any shot in the general direction of an enemy (or vice versa) was an immediate hit or miss, regardless of range.
Doom featured hitscan detection for all bullet weapons.
Quake and Quake II did likewise, though the nailgun, blaster, and hyperblaster fired modelled projectiles; the second game started a long-running trend for hitscan sniper rifles with the Railgun. The Gladiators are equipped with railguns, but have an 0.3 second delay between targeting and firing, allowing you a narrow window to dodge.
Medal of Honor did this, resulting in the infamous Scrappy Level "Sniper's Last Stand" where the player had to face off against eerily prescient hidden snipers with hitscan rifles. Worse, it also means that enemies' shots can continue to hit you while they're flinching or aiming the wrong way.
GoldenEye and Perfect Dark both have fake tracers. In Perfect Dark even crossbow bolts are hitscan.
Deus Ex, where you can bind keys to slow time down and see bullets travel faster than the visible tracer does.
Far Cry makes the fakeness of tracers obvious due to very long ranges in the outdoor levels; firing a weapon at water from long range will cause a splash long before the tracer arrives.
Call of Duty does it for all bullets.
The Turok games do this up until 3 with bullet weapons and some enemy weapons; the fake tracers were particularly irritating in the latter case, since you couldn't dodge attacks which appeared to be relatively slow-moving.
In Killer7, all of the Smiths weapons do this, even Kevin and MASK's, who use throwing knives and grenade launchers respectively.
Fallout 3 weapons appear to be all hitscan when not using VATS. This is most obvious when, through mods, using a scope on a normally unscoped weapon. The enemy will drop almost a full half-second before the tracer projectile reaches them at long ranges.
- The Laser weapons you can use are in fact Hit Scan weapons, due to them being Frickin' Laser Beams. This is their major advantage over the more damaging plasma weapons, whose Painfully Slow Projectiles have a very hard time hitting moving or distant targets, at least without VATS.
- 3 and New Vegas do somewhat avert this for killing shots with the cinematic camera, however; for example, take aim and fire at an unaware Powder Ganger from far enough away with a scoped rifle, if it hits him the game will do a Max Payne-style bullet cam towards him before he drops dead from the critical sneak attack bonus. Of course, you don't have to actually compensate for the Powder Ganger in question moving before you took the shot.
In Halo, most human weapons fire bullets and are hitscan. Covenant weapons, on the other hand, are almost all projectile weapons. Though it seems that the hitscan takes speed into account - this can be most easily seen with the shotgun. Firing it at the end of a wall causes the impact sparks on the near wall to appear noticeably before the far wall. In addition, the bullets (of, say, the pistol) are affected by the movements of the user. Bungie also made Marathon, which used projectile properties for all the weapons.
In Unreal, all of the gunpowder weapons are hitscan, but they have other drawbacks:
- The Automag is the only weapon in the game that needs reloading.
- The Sniper Rifle has the slowest firing rate.
- The Minigun has a slow ramp up and can still be dodged by your opponents in-game.
- The Combat Assault Rifle in Return to Na Pali has no drawbacks whatsoever, making it the most powerful weapon in the game.
Unreal Tournament's version of the ASMD energy weapon is hitscan, but the tracer is particularly noticeable as not being so - because of the small shockwave that appears wherever the weapon hits, you see a small expanding circle of energy that is later joined by the tracer itself.
The Vulcan Cannon in Descent, which is also used by the infamous Class 1 Drillers. Most of the other weapons avert this.
- It's also a major part of the reason why the Gauss Cannon in Descent II is such a Game Breaker, being a Vulcan Cannon with massively increased damage. You can at least dodge missiles and charged Fusion Cannon shots to some extent.
- Descent 3 Nerfs the Gauss Cannon into the Vauss Cannon, though it's still stronger than the Vulcan Cannon. It also adds the Mass Driver, which has a sniper zoom if you hold down the primary fire button and acts much like a Quake railgun, One-Hit Kill and all.
The pistol in La-Mulana is hitscan, despite being a Platform Game. It's also Awesome but Impractical.
The older Rainbow Six games did this, allowing terrorists to get an insta-death shot from any range. And their accuracy wasn't affected by recoil or movement, unlike yours.
The Pistol, Shotgun, Plasma Rifle, and Firestorm Cannon in Turok 2. Averted with the Bow, where the arrows are affected by gravity. (Just like real arrows!)
RoboWar originally had lasers do hitscan damage, but only 1/5 of power input, weaker even than rubber bullets. Lasers were later all but removed from the game and banned.
Borderlands uses projectile modeling for every weapon in the game (with the Siren class having a special ability that jacks up bullet velocity, even!), except for one. The alien-tech Eridian sniper-rifle-style weapon hits instantaneously at all ranges.
Warzone 2100, in spite of animating and tracking individual projectiles, flagged every attack using a hitscan: If the attack was declared a hit, the target would receive damage when the projectile reached the target's location, regardless of whether the target was still there, or how long it actually took for the projectile to get there.
Team Fortress 2: All bullet and melee weapons are hitscan, it is just the graphical tracer effect that looks slower. Stand at a distance and fire at a wall. The bullet hole decal appears instantly, with the tracer hitting half a second later. One can also turn on damage feedback to see it in numbers. Realizing this disparity will greatly increases a player's efficiency, as leading the target to compensate for the non-existent travel time makes you miss.
- Also, while melee weapons initiate a short ranged hitscan attack, they do so only after a quarter-second delay to ensure that hits aren't made before the melee animation completes. The two exceptions to this rule are the Spy's backstab and when the Engineer uses his wrench on any of his buildings.
Lasers in Mechwarrior 4 are hitscan. This, along with good damage and range, made the Clan ER Large Laser the primary weapon of choice for online play for quite some time, well after the Expansion Pack (and later, MW 4:Mercenaries) were released. Later attempts by the fans to balance this only partially overcame this advantage, as lag issues (including the "No Damage Bug") tended to cause some players to miss with other, non-hitscan weaponry.
- Lasers are also hitscan in the other games of the franchise, except for Mechwarrior 2 and its spinoffs.
Subverted in the X-Universe games. Frickin' Laser Beams look like this, but modders have discovered that the game engine treats beam weapons as very fast projectile ones. This is normally transparent to the player because the projectiles are invisible, but occasionally—typically while fighting very fast ships—it can happen that the beam graphic crosses your target but the projectile isn't there yet, resulting in an irritatingly damage-free enemy.
In The Elder Scrolls V: Skyrim, shock magic spells (e.g. Lightning Bolt) are hitscan.

Aversions

Note: For the sake of brevity, this is a list of games which do not contain hitscan weaponry at all. Projectile modeling was common even in Doom's time for certain weaponry (such as rocket launchers, which are never hitscan).

Max Payne was one of the first games to make a big deal of not using hitscan weaponry at all; in Bullet Time, every round fired can be seen as it travels towards the target.
- Particularly notable in that every round on every weapon is fully rendered even when not in Bullet Time. The player can sometimes get a glimpse of bullets traveling past the player and towards the camera even in real time.
  - To show this off, on-target shots from the Sniper Rifle let you ride the bullet to the target. The Fridge Logic is that the game must know ahead of time whether or not the shot is on-target... The Arrow Cam does occasionally trigger for a miss however, at least in the PC version, so presumably it's supposed to trigger when the game thinks there's a high probability of a hit.
  - This is easiest to see in Max Payne 2 when you meet one of Vlad's named mooks firing his AK-47. One of The Matrix mods has a bug(?) that makes Every Bullet Is a Tracer at all times (as opposed to just in Bullet Time), and every shot has one.
Battlefield 1942 and all subsequent games in the series (excluding Battlefield Heroes) also had realistic ballistics as a selling point; bizarrely, even the knife was a projectile weapon which "fired" a slow-moving instant death projectile fixed to the centre of the player's viewpoint.
STALKER did this for all guns (though the off-axis firing means the result isn't necessarily realistic per se), it's also particularly helpful that Every Bullet Is a Tracer if you're sniping as the bullets visibly drop over distance. It did, however, have an extremely strange quirk; the randomisation rules for NPC targeting were also applied to the player. This meant that after you hit someone the game would basically roll a dice to check if you hit them.
- The Gauss Rifle is functionally a hitscan weapon, as it's firing bullets at a much greater speed than the other guns.
America's Army.
Operation Flashpoint: If it goes bang, then the projectile behaves according to the rule of physics.
Sniper Elite also tries to keep bullet path physics as realistic as possible.
Most flight combat games (Ace Combat, HAWX, etc.) require you to lead your shots when using the airplane's main cannons.
It's only apparent at longer ranges, but every bullet weapon in Red Faction has an actual projectile, and the rocket weapons have fuel, meaning that they will drop after a certain distance.
Star Wars Battlefront averts this by necessity, as the nature of blaster bolts (glowing brightly and moving rather more slowly than most bullets) would make Hit Scan weapons very, very obvious.
- Dark Forces even lowers the damage of blasters the farther the bolt has to travel.
- In Jedi Knight, using Force Speed and running into a shot from a blaster weapon would result in more damage than if you'd been hit while standing still. It seems like a decent amount of the damage caused by rockets (especially noticeable with the ones that latch onto you and wait for a few seconds before detonating) was purely from the impact.
Marathon. All bullets, including those fired from rapid-fire weapons like the assault rifle, are tracked as regular projectiles, showing up on the player's motion sensor in the process. Especially remarkable due to this game being released in freaking 1994. Of course, running this on a single core Pentium MMX at 0.05 G Hz with 0.015 GB of RAM was difficult.
- They generally weren't affected by gravity, although grenades were. Also, the speeds Bungie set for most bullets were quite a bit slower than is realistic.
In Silent Scope your bullet's trajectories are affected by gravity, by movement while on a vehicle, the wind, etc., requiring you to Lead the Target. One of the few arcade lightgun games to do this.
Police911, where the bullets were painfully slow.
Unlike its predecessor Far Cry, Crysis has no hit scan weaponry.
Viewtiful Joe bullets and tank shells travel instantly unless you activate Slow Motion before they fire. In Slow Mo you can see the projectile and punch them back.