In video games, a hitbox is the part of an object considered 'solid' for the game's purposes. It would be very mathematically complicated to model all the characters' body parts and check when they've touched, so instead, a rectangular or cubic region of each character is chosen as the hitbox. When two hitboxes overlap, the game knows that the characters have collided; when an attack lands inside a character's hitbox, it has hit the character. Fighting Game jargon usually differentiates the two boxes by calling the attack's a hitbox and the target's a hurtbox; in other genres the term "hitbox" gets used for both.
In the early days it was a box, as a rectangular or circular solid is less math-intensive when doing the collision checks. More modern 3D games have a whole separate model made of hitboxes that closely follows the rendered model in logical space, many including different values for different body parts to enable hits to weak pointsFor Massive Damage.
Sometimes, whether intentional or not, hitboxes don't match up quite right with the graphics, thus producing Hitbox Dissonance. This can take several different forms:
An enemy's hitbox is too small. This makes the enemy harder to hit, and tends to happen with small enemies that are already Goddamned Bats to begin with.
An enemy's hitbox is too large. This is especially problematic for enemies that attack via Collision Damage, and in extreme cases can break Willing Suspension of Disbelief when shooting the air two feet away from the big guy makes him bleed anyway.
The player's hitbox is too small. Although it makes the game easier against enemies (especially when dodging bullets), it can be more difficult trying to land on a platform when you don't know how much platform you have to work with.
The player's hitbox is too large, or extends beyond the visible portion of the sprite. This can be a rather glaring form of Fake Difficulty if your character is a One Hit Point Wonder.
Projectiles' hitboxes are too small. On magic, fire, or energy projectiles, this can be Hand Waved as only the core of the projectile counting, with the aura around it just being gases or debris of some sort.
Projectiles' hitboxes are too large. This can prevent the player from shooting through small spaces or around cover, which may or may not be a good thing, depending on the game.
The hitbox is disjointed: the hitbox and main damaging areas do not follow the physical logic of the attack.
The hitbox for world objects is broken, meaning shots will incorrectly shoot through an object or incorrectly block a shot.
Fighting Game fans tend to explode when they encounter this type of problem. Maybe even the winner will Rage Quit, having unearthed the inherent unfairness. Regardless, it occasionally can be considered a Good Bad Bug.
One of the many, many flaws of advergame Darkened Skye. The hitboxes on the enemies are rather smaller than the models (especially, yes, the Goddamn Bats), while your own hitbox is larger but your weapon's hitbox seems to be smaller. Fights are frustrating, to say the least.
This is a rare example of hitbox dissonance in a static object. In The Legend of Zelda: The Wind Waker, stairs in later parts of the game actually act like ramps, probably because it took too much time to make every tiny step in the stair hitbox (the game was nearly over deadline), so the programmers instead created much simpler ramps instead. However, there was enough time to model every single step in the stair models.
Also, the Moblins' staff swing attacks seem to have an unusually far range. Link will be standing three feet away from one, and in the blink of an eye, he's been flung onto the ground. This also seems to be the case with the Poes' scythe attacks from The Legend Of Zelda Twilight Princess.
The original Ninja Gaiden trilogy nearly falls into the realm of Fake Difficulty because of its poorly sized and placed hitbox areas, both in the player character as well as in the enemies. The Act I boss of the original suffers from this too. You can have your sword be centimeters from hitting him, and you'll still do damage.
In Toy Story, the hitbox for Buzz during the gas station fight is noticeably large when he's bounding around the stage, so you get hit unless you're directly below the arc, making this fight unfairly hard.
In Bugs Bunny Crazy Castle 2, both Bugs Bunny and his enemies had tiny hitboxes, which could lead to odd situations where Bugs Bunny could walk right through them without any harm. The weapons Bugs could pick up, on the other hand, had large hitboxes, and in most situations, had no trouble hitting an enemy's small hitbox. It almost completely works in the player's favor, at least, and since Bugs is a One Hit Point Wonder, you may need all the help you can get.
In Battle City and Tank Force, players and enemies actually "snap" from one half-tile to another even though sprites seem to go smoothly. This was done to ease navigation as the problem was apparent in Tank Battalion.
The hitboxes for Chief Scalpem/Wigwam's knives in Sunset Riders don't always seem to be in the same place as the physical knives, meaning that in some cases, the safest place to be is directly in their path.
Alien Syndrome for the NES had a severe case of the "bigger" kind. In some cases, you could shoot the air and still kill your foes, and likewise you could die from touching the air near them.
Presumably this occurred with things like walls in Superman 64, since a few cases shown in The Angry Video Game Nerd's review had the player get stuck despite being about three feet from the actual wall. See here
Racing series Burnout and Excite Truck\Bots also use this, with "near miss" and "tree run" bonuses. The "small hitbox" is your whole car in these games though, and the "large hitbox" is the area around it.
Many early driving games have entirely rectangular Hit Boxes, which is really egregious when it extends all the way to the side-view mirrors.
Soul Calibur's custom characters suffer from this. Since all custom characters are the same height but use a standard character's weapons, the standard character's hitbox is mapped onto the custom character, which leads to problems when using the style of a particularly tall or short character.
V tries to avert this by letting custom characters' heights be chosen. A star is above the choice that matches the standard character's height the closest.
Tekken 5 was pretty notorious for grounded mids, especially in wall combos. To clarify for non-Tekken players: some mids do have the property of hitting a character on the ground (downward chops, rising kicks, etc). But there were a lot of straight thrusting attacks that hit a person almost completely lying on the ground or rolling to the side. One big offender was Anna's Tread Water kicks to Judgement Kick (f,f+3,4,3~b, 3), the last of which was a front kick which would hit a grounded opponent or sometimes even an opponent behind Anna.
During the release week of the console ports for Tekken Tag Tournament 2, it was discovered that when crouching, Kunimitsu not only avoided every high-hitting attack in the game, but PLENTY of mid-hitting attacks in the game, which is completely unheard of. It has since been fixed as of now.
To clarify on the Kunimitsu crouch glitch, one of Tekken's many systems is the crush system, a type of rock-paper-scissors mechanic. Certain animations (mostly, but not strictly attack animations) allowed characters to avoid a specific height of attack; jumping attacks such as hopkicks avoid low attacks, lunging attacks avoid high attacks and some mids and so on. Crouching characters (even those of larger stature such as the Bears and Ogre) can evade highs and block lows, but are highly susceptible to mid hits. Kunimitsu essentially breaks this universal rule when she crouches, forcing more whiffs than any other can, which can be severe considering how harsh Tekken's other systems can be. As stated above, though, this was fixed in later patches.
M.U.G.E.N - Disjointed hitboxes are also one of potentially many signs of a badly made character. Remember, the quality of the sprite has nothing to do with how the character gives nor receives damage, as those are programming values.
Super Smash Bros has a lot of these problems, partially due to the fact that a single attack will have several different hitboxes with sometimes wildly different strengths.
Ganon's down special continues for about four seconds, but by the third second it stops doing potential damage. This creates the odd situation where you should be going through someone with your foot but they smack you back. More evident in his recovery (up special) where not only is it unlikely that you will latch onto an opponent, but the punch at the end will most likely never hit.
Snake's side and up tilts are absolutely ludicrous in this regard. Both of them have hitboxes which strike at least a foot in front of where his feet/hands end. This is especially noticeable with his up tilt, which makes Snake kick straight upwards into the air and yet can hit an opponent seemingly three feet in front of him. This is because in development at some point snake's model was resized, but they forgot to resize his hitboxes, resulting in all of them being twice as large as the model.
In Melee, Marth and Roy's grab hitboxes are twice as long as they really should have been. Their standing grabs actually outranged Yoshi, despite them having seemingly standard grabs and Yoshi having an obviously ranged grab.
Quite a few characters can hit people standing behind them thanks to attacks with hitboxes that extend behind their back or over their shoulder.
King Dedede's infamous chaingrab is due to his absurdly long grab range, which extends quite a distance from his actual hand.
Hattori Hanzo'sLimit Break in Samurai Shodown III had a hitbox that stuck around nearly a second after the actual explosion. Worse, it did not combo with the rest of the attack, meaning that a person who blocked the attack could let off the block a moment too early, and end up taking the full brunt of it anyway.
It is even more noticeable with Hakumen's Yukikaze. The thing hits the entire horizontal plane and even double jumping will not save you unless you have moves that rocket you farther up screen.
NES version of Yie Ar Kung Fu suffered for this quite a bit where a hit was registered a miss and vice versa. The fact that the enemy was mostly made out of background instead of sprite contributed to that.
Killer Instinct was known for allowing some truly absurd crossups - essentially, kicking your opponent in the face by jumping over their head and grazing the air a metre behind them with your left knee.
As you'll find below, Touhou is famous for how important your character's hitbox is. This even carries over to the fighting game spinoffs, where sometimes dodging that instant-kill spellcard or that one bullet that would knock you out upon hitting relies solely on your knowledge of hitboxes.
Street Fighter III has a problem with so called "nails"note named because people think the characters are only hitting the enemy because they forgot to trim their toenails or nails. where attacks would extend just a little farther that they should, as seen above in the quote.
Marvel vs. Capcom 3 has quite a few of these. Most notable is Hulk's standing H, which can hit an opponent directly behind him, even though he's swinging his fist the opposite way.
First Person Shooter
There's nothing quite like putting bullet holes into empty air in MAG.
In Doom, for collision with objects, monsters, and projectiles, everything is essentially treated as having infinite height.
The sprite for Revenants is noticeably taller than their hitbox. The difference between sprite and hitbox doesn't manifest as aiming difficulties, but it allows Revenants to walk in tunnels that they shouldn't fit into.
The Spider Mastermind seems to take up space at least four feet farther on each side than it appears. This often leads to it getting hung up on walls and other monsters when used in custom levels.
The plasma rifle has the "projectile's hitbox is too large" variety.
There's also a bug where a bullet can completely fail to hit its target depending on where the shooter and the victim are standing in open space, even at point-blank range. Click here for details.
Projectiles that impact with the "ceiling" of sectors which have an open sky immediately disappear. This is rarely triggered without playing in source ports which allow freelook, however.
Hitbox Dissonance also factors (deliberately) into the final boss of the Doom 2, "The Icon of Sin", whose hitbox (actually John Romero's disembodied head) is located at the end of a tunnel on the boss monster's forehead, which is nearly impossible to hit directly, and can only be reliably damaged with splash damage from rockets (which, due to the engine not being true 3D, is a cylinder of infinite height rather than a sphere).
There's NO difference on how hitboxes are handled between actors, they always start from the 0,0 point of the sprite's offset and builds UP. The disorienting part comes from when you use WAD or PK 3 editors such as Slade and the automatic projectile sprite offsetputs the offset coordinates in the dead center of the sprite.
Added to that, the projectile height has no impact on the parameters for firing projectiles. The projectile will always be fired from a specific "center" from the calling actor. Low ceiling and tall projectile? Will hit the ceiling even when the sprite doesn't.
The Titan, being essentially a twenty-foot reptilian gorilla, isn't very compatible with the simple collision cylinders used in the game, thus ending up with at least a minor form of the "shoot the air next to him" trouble. That said, this is probably a good thing for game balance due to his immense power and durability.
The pupae and predator enemies are best taken out from afar, since once in melee range, their narrow collision cylinders make them nigh-untouchable.
The Spy of Team Fortress 2: Landing a successful backstab (which is instant death) depends on the view angle of the victim, and not the actual pose of the character, causing dissonance when combined with some animations. This is in addition to lag and the game's rather odd way of calculating melee hits (using the player's bounding box) and, well, you end up with a lot of sidestabs and facestabs. Numerous tweaks and updates have gone toward trying to get it right, though you can't please everyone.
To the Spy's considerable advantage: a disguise does not change your hitbox◊. A headshot to your fake head will hit you in the torso if the model is short enough.
To add to this: the Spy can disguise as his own team, so the enemy sniper may not even know the player is a Spy.
Better still, the Sniper is taller than the Spy. It's very possible that what would have been a headshot on a real Sniper will go straight over your head.
With the Sniper's bow unlock, the Huntsman, it's quite possible to aim a few inches to the left or right of an enemy's head and still get a perfect headshot, as it uses the projectile hitbox (which is the same for every class) rather than the bullet one (which varies by class). The arrow, rather than sticking the body as it normally would, simply disappears.
Being hit by an enemy with a melee weapon in general is wonky - It will often appear the enemy is several feet from you and hitting you with a really long fist. This is because, rather than using hitboxes, melee attacks use one big map-aligned cube to determine hits.
Further compounding the issue is several melee animations, namely all of the Pyro's weapons and the Demoman's two-handed weapons, are disjointed relative to time. What this means is from your perspective, the attack hits while the Pyro/Demoman is still winding up for the strike. The Pyro/Demoman don't see this, however; their first-person animations are synced properly.
The Engineer has the opposite problem, which can be demonstrated by aiming at a wall and using melee. It will leave a strike mark in the wall AS HE BRINGS THE WRENCH UP to swing.
Taunt kills are even more silly. It's possible to temporarily dislocate the hitbox from the onscreen model, making it so that, for example, Sniper's arrow stab shanks someone directly behind him. Even without that, the range for several of them extend far enough to where the attack's animation doesn't have to actually touch the victim to do the damage. Most taunt kills even hit above you, so if your enemy is standing on your head they still get shafted. This isn't even touching on Heavy's ability to shoot his Finger Gun a full 90 degrees above/below where his arm is pointing.
Speaking of taunts, animations like taunts and post-round humiliation stances (and others like spy crabs) do not have matching hitboxes, meaning you need to shoot where their head would be if they weren't taunting, spycrabbing or being humiliated (thankfully, taunting opponents are immobile and humiliation gives you unlimited critical hits, mitigating the issue).
This actually becomes a problem in Mann Vs. Machine as robots that hold the bomb long enough start giving out Status Buffs but taunt to give the playering an opening. It can make killing them as sniper before they move again quite frustrating.
When zoomed, the Sniper's hits are calculated by precision, limb-for-limb hitboxes. When not zoomed, he gets the same single box as any other class. Since the sniper rifle is perfectly accurate, this actually means that you are more likely to hit someone with a non-scoped shot. Of course, without the scope it only does 50 damage maximum with sharp falloff.
In Counter-Strike: Source, players' hitboxes actually lag a step behind their models. This can lead to some frustrating missed shots or WTF deaths. This happens in just about any online shooter to some extent, varying depending on lag and netcode.
For the technically-inclined, an excellent article on how Source engine games (Half-Life 2, Counter-Strike etc.) usually handle this can be found here. Making sure that gameplay seems fair (even at the cost of it actually being fair) is an important priority for developers who want the game to be any fun.
Call of Duty frequently has seemingly wonky hitbox detection, as seen from killcams in online play. The hitboxes are actually very, very detailed, but even a small amount of lag (as in, normal amounts of lag), can turn a kill into a miss. Headshots are, therefore, best pushed into the realm of luck rather than skill with anything other than a sniper riflenote except against players using the "Last Chance" perk/deathstreak, where, possibly due to the massively different pose than usual when it's activated, headshots tend to be much more common. Games in the series that try to compensate for lag often end up making this even worse - resulting in, say, a sniper standing right next to a window, aiming down, and killing you along the wall below, when from your perspective all that's even visible is the very tip of his gun's barrel pointing straight forward.
"Normal" hitboxes that players are used to demonstrate this trope. The premise is simple: players feel cheated when their bullets go through enemies, but badass when they're the ones dodging bullets. So, heroes tend to have smaller hitboxes than their sprites would suggest - this is why Mega Man puts his foot through the floor whenever he lands from a jump.
Killing Floor had effectively broken hitboxes on a pair of high level monsters, one had his head hitbox buried in his neck in such a way that it was more or less impossible to hit without attacking from above, another had his head hitbox floating in mid air above his left shoulder. This meant that new players attempting to gain head shots by shooting at the head found it impossible. Veterans that had learned about this and knew where to aim or how to exploit AI could hit them, but of course when this bug was finally fixed there were cries that the devs were pandering to the scrubs and had ruined the difficulty.
In Left 4 Dead the Hunter's hitbox is actually a ways ahead of him, as various Youtube tutorials have pointed out. One must take this into account when trying to melee them during their pounces. This has also extended to the Jockey and the Spitter in the sequel. The Jockey can leap and latch onto a survivor from at least 2 feet away due to its ranged hitboxes and the Spitter's acid patch has a slightly larger hitbox, leading to players being damaged from the acid even though their character models aren't physically standing in the acid.
The sequel also has wonky hit detection with melee weapons. Sometimes you can clearly hear the weapon smashing into a zombie's torso, indicating you hit them, but they may sometimes not take any damage at all and will continue to attack you. This problem is more noticeable with short ranged melee weapons like the machete and nightstick due to them having fewer hit boxes for being short weapons. One would expect this to happen in an online game where lag can pop up and mess with the timing of your swings, but this can also happen in single player mode, which is offline.
The survivors generally have the same sized hit boxes so that no survivor has an advantage over another survivor, but Zoey's hit boxes are slightly smaller than everyone else.
In Metroid Prime 2, Emperor Ing's second form takes an absurd amount of damage from the Screw Attack if you land near his feet. Not a direct hit, you must land near him. He'll crumple in under a minute. Also, his chin seems to block many blasts if you shoot him from ground level; try jumping. Note that the Wii rerelease fixed this.
When diving to the ground in Battlefield 2, the animation shows a running character jump forward before landing on the ground. The hitbox, on the other hand, changes to 'prone' instantly, making the diving character very hard to hit, even if you know you shouldn't aim for the airborne body but for the ground below him.
The hitbox wasn't the only thing that went straight to prone. So did the diving players accuracy. This is why before it was fixed in a patch Dolphin Diving was the biggest Game Breaker the series had ever seen.
Battlefield 3'' has major examples of the physics object hitbox issues. Many of the random items on the floor of the world like boxes or pieces of rubble are only client side, not server side. Which means the rubble, box or crate you are hiding behind on your screen is actually nowhere near you on your opponent, meaning you are standing out in the open from his view.
Postal 2 has an egregious example with Gary Coleman, especially noticeable when he gets into a fight with NPCs that ALWAYS aim for the head and make puffs of blood appear ABOVE Gary's head. This is presumably done to maintain balance in multiplayer and avoid the issues that GoldenEye had with everyone trying to pick Oddjob.
It's possible to create this with custom skins in some games, including the original Unreal Tournament, if the skin is sufficiently larger than the normal character model. Snipers trying for headshots will have a much harder time hitting the character. Then again, this can backfire as less skilled/experienced players can get accidental headshots while attempting (generally more reliable) body shots.
The zombies in Nazi Zombies seem to have hit boxes that are as large the doors they are trying to maneuver through. This has resulted in many a game ended because of one zombie taking up the entirety of what appears to be a double door.
Pac-Man has a smaller hitbox than it seems. Especially apparent in Championship Edition series. This is an odd case in which his hitbox is based on his position in the maze rather than his actual sprite. It's because of this that you will very rarely see Pac Man pass right through a ghost without dying at times.
This particular dissonance is due to the code requiring both the ghost's and Pac-Man's sprites be in the same grid box at the same time. If either one is even a pixel outside of the grid box, it doesn't count.
The Robot Ninja Haggleman games from Retro Game Challenge gives enemies a slightly larger hitbox than the size of the enemy. This means that if you approach from the wrong angle, you will get hit without actually touching the enemy. This is particularly bad for Dark Hagglemen, who have an animation where they laugh after deflecting your attack - but which doesn't turn off their hitboxes.
World Of Warcraft has some examples of both. Many bosses have very large hitboxes to make it easier for melee classes to attack them. Kologarn for example has a hitbox that is so large that you can stand near his right arm and use an area-of-effect attack to hit both of his arms and his body (his body and arms have separate hitboxes). Some bosses on the other hand have very small hitboxes. Saphiron for example has a hitbox that's about the size of his body, with his head and tail extending outside of the hitbox, meaning melee classes pretty much have to stand right under him.
Sapphiron is a stonking great dragon, so if his hitbox really covered the same amount of ground he did, it would fill the whole room.
Thaddius: one of his boss abilities is to charge players up with either positive or negative charges. If the two groups stand too close together, you all die, so his hitbox is unnaturally big, or nobody would ever be able to kill him.
Lots of wipes were caused by some douchebag throwing Baby Spicenote An item which lowers the size of mobs, but has no non-cosmetic effect on him.
Kel'thuzad can ice block a player, which will chain and ice block anyone else within 10 yards of that player, who will then chain to anyone within range of them. Generally if this happens to more than a couple players at once, it's a wipe. His hitbox is much larger than he is — just big enough that three melee classes (usually offtanks in case the main tank gets blocked) can stand at the points of a triangle around him and still stay 10 yards apart. On the flip side it means that any other melee classes in the group need to stand back and watch, while also not getting too close to anyone else.
A common method of dealing with this, when in a group that has lots of melee types, is to exploit the lack of collision detection by positioning people directly on top of each other. If one of the melee clumps freezes, then yeah they're all hurt, but it's manageable and won't chain to anyone else.
The proto-drakes in Wrath of the Lich King are pretty notorious for lousy hitboxes. Since they fly you don't often have a ground reference and the ground-hitbox-indicator-circle-thing (new trope?) is often hard to see and irritatingly small, which ends up with the player often getting "Not in range" or "You are standing behind him you dolt" messages when trying to melee.
Any player character, especially after factoring in server lag. You can get Ambushed or stunned from twenty feet away, shot (which you supposedly can't do at close range) between dual-wield melee swings that are supposed to go off simultaneously, be standing on top of an opponent inside their rendered model and see "too far away", etc.
At release, this was notoriously bad for feral druids in cat form, because the character in that form is a long, low-to-the-ground quadraped, the hitbox was still shaped like a humanoid (tall and narrow), so a kitty had to look like it was nearly inside a mob before it counted as being within hit range. This problem improved over time with patches.
Some attacks home into a certain body part for cosmetic effect, specifically shadow priest spells, being psionic in lore meaning they usually appear at and around the head hitbox. Sometimes on non-humanoid mobs the head hitbox is in some very odd places. Sometimes the hitbox wasn't placed correctly such as in Karazahn where mind flaying skeletal horses before the first boss made you HIT THE WALL about 20 feet away, needless to say, it was pretty comical to make fun of Spriests for damaging the deadly wall ghosts.
In a less violent sense, this applies while trying to interact with large sprites - collect items from a monster you killed, or talk to an NPC - when you might have to find a specific (unintuitive) spot to stand in order to be "close enough" to the core of the sprite. Sometimes you have to stand right inside the sprite, or inside its tail, or the like, in order to be close enough to interact with it at all.
Some more recent offenders include Lord Marrowgar, the first boss any player will see in Icecrown Citadel. For the uninformed, this guy is a big, floating mess of bones with arms and a really big axe. The standard manner of fighting him is to stand inside his hitbox to avoid a nasty line-of-fire-along-the-ground attack. However, hunters are required to stay at least 5 in-game yards away from him in order to use their ranged attacks (their only really powerful ones). This guy's hitbox is HUGE, and very difficult to actually pinpoint due to the fact that he's, you know, floating above the ground and doesn't directly touch the floor for reference. If a hunter gets caught on a bone spike, they'll likely be halfway across the room, away from notice if people aren't paying attention.
Tauren players have the largest hitbox of any race, this caused issue at the beginning of arenas, when Tauren melee had a hitbox large enough to allow their weapon swings to pass through the pillars in the nagrand arena, resulting in a game of maypole where the unlucky recipient couldn't even defend themselves, predictably, this was fixed pretty quickly.
The stone drake Slabhide is particularly problematic on Heroic difficulty due to this. During the fight he unleashes a crystal spray that people have to hide behind fallen stalactites to avoid. However, if people are inside his enormous hitbox the attack won't register the stalactite as blocking it and the attack will still damage them, even though by looking at the screen there was clearly a giant block of stone between the character and the drake.
The Ancient Smoldering Behemoth, one of five bosses from the daily quest chain in the Molten Front, is easily the largest of the monsters, but has an extremely small hitbox, so that you have to stand underneath him in order to melee him. The problem is that he also uses an area of effect attack centered on himself (which you must avoid for an achievement), making it more difficult to run out and back.
Players often shout abuse at the plesioth. Its hitboxes are grossly misaligned, which makes dodging its attacks extremely irritating. Its "hipcheck" — an attack where it slams you with its hip — is infamous for having a hitbox several meters bigger than the creature's body. Most people, even the most dedicated swordmasters, decide to make a bow solely to be able to snipe the Plesioth from beyond its wonky hitboxes' range.
A similar issue happens whenever a monster attacks by spinning in place to whip its tail around (which just about every wyvern or dragon with a tail does). Even if the monster is so tall that it looks like its tail would just whiff over your head, it'll knock you down.
Note that wyverns with similar body types don't necessarily have the hitboxes scaled to match. It's entirely possible to avoid a gypceros's tail sweep by standing directly under its crotch, but trying the same trick with a Monoblos or Diablos (who are both quite a bit taller than a gypceros) will get you clobbered.
Diablos has another problem in that it can hit you with its club tail even if said club is lying severed on the ground.
This has been improved somewhat in Monster Hunter Tri, where you can avoid some tail swipes at distances that would have surely gotten you thwacked in earlier installments.
In terms of your own attacks, the hitboxes are slightly askew. When fighting against a large monster, it can be difficult to Attack Its Weakpoint. If even a slight bit of your swing hits the hardest armor, your attack bounces off, the monster takes little damage, and you stand there like an idiot for a second while the monster has time to attack. This makes the Barroth a Wakeup Call Boss, since its the first monster to be mostly covered in hard plating.
It also works both ways though, as since most of your melee weapons involve swinging them around, if you're under a monster and your weapon just grazes their weakness, the game will register it as a full-fledged hit. There are some stories going around where people have cut off tails just by poking the tail with a weapon.
The Hitbox on a Mobile in Gunbound is only one pixel wide. This means that you can unleashe a Macross Missile Massacre or Bullet Hell on an enemy, completely obliterating the ground beneth them, only to have them still be alive, perched on that one pixel your blast did not destroy. This also makes it insanely hard to kill the opponent, as most projectiles don't explode unless they connect with another hitbox, and with the ground gone and the opponent being one pixel wide, it's considerably harder now to kill them.
The Devs had said this is the reason why Rularuu isn't available to fight in City of Heroes, even though a model of him exists in the game's assets. As it stands right now, a character standing on Rularuu's shoulder would need a snipe-range power to hit him.
The now discontinued space MMORPG Jumpgate at one time used a simplistic ovoid shape to determine if ship models were hit by missiles. For many of the designs the difference between hitbox and ship model was minimal, but some ships had their missile vulnerability increased greatly, in particular the Octavian Phoenix. The design's a long and slender fuselage and long downward-angled wings greatly expanded the missile hitbox and increased the ease in hitting it.note The ship already had the slowest acceleration of the three "fighter" class ships, which combined with its heavy gun firepower made it a favorite target for missile-heavy opponents, even when disregarding the hitbox issue.
Mega Man 3 has a lot of this, because Mega Man's hitbox is a rectangle. Mega Man's hitbox is consistent for all the NES games (not including MM 9, which is an entirely different engine), but it's actually possible to see it, if briefly, every time the Blue Bomber gets hit. The white "damage field" that blinks through Mega Man is exactly the same size of the hitbox. It's slightly taller than Mega Man, and slightly wider.
Where it gets ridiculous is when Mega Man fires his weapon while standing still. He leans forward, extends his arm, and projectiles emerge from the end, but his hitbox remains the same, and thus the entire outstretched arm has no collision detection at all! He can shove his arm into any obstacle and launch bullets from inside it if he pleases. In games where Sniper Joe's shield has its own hitbox rather than simply a shielded state for the whole sprite during certain animations, Mega Man can tiptoe up to Sniper Joe, reach past the shield, and shoot him directly, without having to wait for Joe to lower his shield.
This is incredibly infuriating in Megaman 2, where sometimes, even being barely out of the reach of a spike or enemy will count as damage or death. The penultimate boss, Wily Machine #2, also possesses round projectiles with larger square hitboxes, making defeating that boss all the more difficult to do.
The Apogee platformer Pharaohs Tomb had rectangular hitboxes around everything, which could result in the player character being killed by something he apparently wasn't even touching when the corners of their hitboxes overlapped. There were also several places where, in order to jump over a wide gap, he had to walk right out onto the edge of a ledge until only the last pixel-column of his hitbox was still on the ledge — at which point he appeared to be standing several pixels out into thin air.
It gets stranger: You could actually jump to kick the monster into going the opposite direction and even walk on top of a monster's hitbox. It was up to you to stay on top; the monster wouldn't carry you along.
This is Hand Waved in the manual: it is stated that you need some room to fire your weapon, so you can't kill enemies if you stand too close; this is actually because your hitbox will already touch the enemy at that point.
In I Wanna Be The Guy, The Kid's hitbox does not include the Cape Of The Hero or the Very Small Gun. That's extremely little difference, but it's required that you take advantage of it to be able to pass certain spike traps.
It also does not change during the vic viper segment, giving the whole thing quite a Bullet Hell feel.
In Ice Climber, the hitbox doesn't match the player while jumping which can often cause a player to go through floors while or not hitting enemies while being in the air.
Bugdom, a game that came free with the iMac, is another game with box-shaped hitboxes, which becomes rather obvious given the shapes of some enemies. This is most ridiculous when fighting non-flying bees, which both lack collision damage and essentially have invisible platforms hovering a few inches above their heads.
Tails' hitbox in Tails Skypatrol is only one pixel high, but the enemies have larger hitboxes than they should to make up for it.
One specific enemy from Sonic The Hedgehog 2, Shellcracker in Metropolis Zone, has an outright counter-intuitive hitbox. When his spiked claw-on-a-chain is extended, hitting him near the base of the chain hurts you. When his claw is retracted, hitting him on exactly the same spot hurts him.
NES game Treasure Master is all about this. First of all, your character's front hitboxes are very good and such, but however, if your back is at the enemy and enemy shoots you for an example, the projectile hits you from space where you could fill another protagonist's sprite. Enemies' hitboxes aren't bad, though.
Canabalt invokes this on purpose for the player's comfort. Buildings extend a bit past their visible right edges, and crates' hitboxes are a mere two pixels tall.
The boss Anubis Rex in Pac Man World is filled with this, as a result of the developers running out of time for proper playtesting.
In Super Mario World, the giant Big Bubble enemies have really tiny hitboxes, making it hard to Spin Jump off of them.
In Super Mario Bros, Super Mario's hitbox is normally twice as tall as standard Mario's, which makes sense. Crouching eliminates the top half of the hitbox, rendering it the same size as standard Mario's, which also makes sense. Crouching while underwater and then swimming causes Super Mario's hitbox to remain at half-height, causing enemies to pass through his upper half harmlessly, which does not make sense.
Real Time Strategy
Allegiance, being a team-based strategy/space combat hybrid, is especially susceptible to such problems, since flying every type of ship needs to be a fair experience for every player. Sometimes, the hitbox for a spacecraft with a complex shape oversimplifies the object's geometry a little too much. At the extreme, there is one ship that looks very small, with several thin wings, but acts as if all the wings were joined by solid surfaces, making what looks like a compact and difficult ship to hit an easy, bulky target in reality. There are also small, but annoying problems with the hit-boxes of a few space stations, which can be a problem since player ships often have to dock at these, and bumping into invisible walls when it looks like you should be flying into a docking bay is never fun. Fortunately, only a very few models suffer from these issues, and only require a little extra care. As the game is being developed by fans, there have been a number of attempts to create new hitbox models and fix these issues; some progress has been made, but the solutions aren't always easy to implement in practice. (Not to mention that in a few cases, some players have gotten used to the hitboxes, and don't want to see them fixed!)
In Defense of the Ancients: All-Stars, the Keeper of the Light's Illuminate spell uses an effect similar to the Shockwave spell in Warcraft III. However, the area covered by the spell is a lot wider and somewhat longer than the visual effect, meaning that you can "dodge" the shockwave and still lose an assload of health.
Rhythm Games have a variation of this called the "timing window", which refers to how much a player can be off from the exact beat a note falls on when he/she hits that beat (graphically, how much of the note needs to overlap with the "hit zone", assuming a constant speed) for the note to be counted as a "hit". Some games, especially those created by Harmonix (Amplitude, Guitar Hero, Rock Band) only differentiate between "note hit" and "note missed", while other games (most Bemani games) have several levels of timing windows that award different amounts of points, or differentiate between a "close miss" and a "way off miss" by punishing you more for the latter. The exact width of these timing windows differs widely between games (and sometimes within the games), and you can guarantee that the type and width of these timing windows is a hot topic on forums where these games are compared.
Rhythm Heaven is a compilation of mini-games that are all hit-or-miss timing windows, but the windows seem to vary for each mini-game. Generally, the simpler the game, the harsher the timing window. Most of the games have either a near-hit or near-miss animation, but few if any have both. Not to mention the Space Shooter endless game that cuts down the timing window as you go.
Even though the series' mini-games don't all give clear visual indicators of whether you almost or completely missed, there's an auditory aid in the form of either a claves tapping when you almost miss, and the telltale "boink" noise when you totally miss a beat.
O2Jam's timing windows are out of whack. First, the timing windows get faster as the song's BPM goes up. Second, they loosen when you use speed modifiers. Conclusion? You get punished if you're more comfortable with lower speed mods than higher speed ones.
DJ Max Technika also suffers from faster songs having smaller timing windows.
The GAMBOL Ascended Glitch in Beatmania IIDX deserves a special mention. Originally, it was one of the easiest charts in the game, but a bug caused it to have much tighter timing windows than any other song in the game, making it easy to clear but extremely hard to score well on it. The song has since been "fixed" to use the standard timing windows with the same chart on Normal difficulty, but retains its Hyper difficulty with the bugged timing windows, as well as having an added Another difficulty chart in the PS2 version of IIDX 11: RED, with the exact same chart but with ridiculously small timing windows that make it quite hard to clear. Newer installments in the series now have the "GAMBOL Judge Hyper" and "GAMBOL Judge Another" Easter Egg codes, which allow you to use the tightened timing windows on any song at all.
Fortunately, the latter incarnations of Guitar Hero allow you to manually synchronize audio and visuals with controller input. Rock Band 2 (and later) guitars have light and sound sensors that are used to precisely measure the audio and video lag.
The hit boxes in Guitar Hero and Rock Band are a point of contention among high-level players. In general, the timing window in Rock Band is pretty moderate, but the window shrinks when notes are placed very close together, which leads to Fake Difficulty on the hardest songs in the game (this is lessened in Rock Band 3, which has a new mechanic for extremely fast and\or imprecise strums and trills). Guitar Hero, on the other hand, is known for timing windows so big that "rhythm" is no longer a necessity. This is generally compensated for by including songs that are, for lack of better words, "walls of skittles".
There are a few jarring instances in the Parappa The Rapper games. This is the reason that Stage 6 of Um Jammer Lammy is one of the most hellish in the series; even nailing the notes perfectly will drop you down to a "Bad" rating. You won't get through without freestyling.
In osu!, beatmaps have OD and AR values, OD determines how small the timing windows are, and AR determines how much time it is between a beat appears and the moment you have to press it (also changing the approach circle speed). Normally, maps with high OD also have a high AR, so timing feels right. But there are some beatmaps (specially older ones) that have a high OD and low AR, leaving you with no precise enough visual cues to have decent accuracy: If you see the approach circle is exactly over the beat circle, you can still receive a 100 (when the max is 300), since the approach circle takes more time to pass over the pixel-width border of the circle than the time window's length. Also, with maps with high AR and very low OD (not commonly ranked) or easy ranked maps, you can get a 300 even if the approach circle is several pixels off from the beat circle.
That, alongside the fact that high refresh rate screens are uncommon, are the reasons most players use skins with approach circles and beat circles borders measuring several pixels, and rely almost exclusively in sound cues instead of vision for timing. Players that can get the timing naturally can usually play with Hidden mod (no approach circle, and the circles disappear moments before you have to press them) without any decrease in accuracy.
Role Playing Game
This is part of what makes the infamous Cliff Racers of The Elder Scrolls III Morrowind so bad: the hitbox is misaligned so that it manages to both hit when it shouldn't and miss when it should have hit. Fortunately, getting below them and aiming for center of mass is pretty reliable. Once you kill them the hit box still haunts you, as you need to remove the corpse to be able to grab anything near it or you will attempt to loot its plumes instead.
Fallout 3 suffers this with the surrounding static models and their collision meshes. There are many occasions when one's line of shooting is very close to what is seen as an obstacle, but when one actually fires, they hit an invisible barrier, thus not hitting the target and subsequently alerting them to your presence and location if you were sneaking. The worst offender is the derelict subway car mesh.
In Melee combat, the range where you can activate VATS is longer than your weapon's actual range. You can effectively teleport about 10 feet to punch or chop your target. This is important since otherwise they tend to stay right out of melee range while retreating.
Fighting against other hunters in Phantasy Star Online is harrowing, as you need to land a blow directly in the center of their bodies in order for it to register, unless you're using a gun.
In The Elder Scrolls V Skyrim, the (airborne) Ice Wraiths can be damaged by hitting the apparently empty space beneath them. There's also some occasional examples of arrow hitboxes and target hurtboxes not meeting up like they should, which are frequently pointed out to the player in long, loving detail as your shot gets a slow-mo special killcam, perfectly articulating the arrow's flight through the air, through the enemy's render, and passing harmlessly out the other side, having completely evaded anything that would have caused the CPU to register a hit.
Talesof Eternia has downright terrible hitboxes on the enemies, especially compared to the rest of the series. One can be right next to an enemy, slashing away a dozen times, and only hit maybe once or twice while the other attacks go right through them, and if 2 or more enemies end up overlapping, the attacks will hit one enemy and not the others. However, the PC hitboxes don't have the same issues for enemy attacks, meaning that the enemies can easily interrupt your attacks, so keeping enemies in hitstun for long like in the other games is downright impossible.
Shoot Em Up
Some Bullet Hell games (such as Espgaluda) feature a tutorial at the beginning which, among other things, explicitly shows the ship's/character's hitbox. Usually represented by just a small circle in the cockpit/engine/torso and with a flashing arrow labeled "HIT".
The 'graze' mechanic in many Bullet Hell games involves two hitboxes- one very small (sometimes just a few pixels), which is fatal if struck, and a slightly larger one that gives extra points if bullets pass through it. This encourages players to take extra risks by getting closer to the bullets as they weave through the patterns.
Raiden DX has the graze bonus, despite being a non-Bullet Hell shooter with a ship-sized hitbox released in 1994.
Raiden Fighters brings the hitboxes closer to Bullet Hell-size, with the Slave having the smallest. However, if you're using the Judge Spear version of the Slave (which has the Judge Spear's game-breaking bomb), your movement speed becomes so fast that grazing becomes dangerous and impractical.
Raiden IV also downsizes the hitbox, to accomodate the denser enemy fire, and also has a grazing bonus.
In Border Down, the hitbox in the middle of the ship is small and enemy shots can pass through like other shmups. However, the ship will blow up if the ship itself, not the hitbox, runs into anything solid. Almost every other shmup these days will allow the player to put almost half of whatever they're playing as in walls and other obstacles as long as it doesn't hit the hitbox.
rRootage and Parsec47, unusually, explicitly show the hitboxes of not only the player's ship, but also the bullets.
Genetos has a similar feature, but it's optional, because it can be distracting. It's off by default, but you can hit G to toggle it.
Both your ship and some asteroids in the original Asteroids had issues where they could appear to be hit on the side and survive, which makes this Older Than the NES.
Transformers Convoy No Nazo has this in spades. To begin with, enemy hitboxes are far larger than their graphics might suggest. On top of that, your own character is a large robot to begin with, and the game is extremely biased when it comes to hit detection - your own projectiles have to hit enemies dead center to hit them (and they're often very small to begin with) while enemy projectiles only need to barely graze you to score a hit (which is enough to kill you).
Bangai-O Spirits has the Bat weapon, which has a hitbox larger than the range it swings through. This means you can swing at enemies a few feet away from your bat.
The playable characters' hitboxes are quite a bit smaller than their sprites. Focusing will show you it, except even that is a bit larger than it actually is — especially for Reimu, who has a smaller hitbox than everyone else (something that fans joke is a combat application of her power to eat sweets and never get fat).
The bullets' hit-boxes themselves also tend to be tinier than their sprites (for example, you can safely fit the characters' entire hit-box into the sprite of the bigger bullets, or go through what seems to be a solid wall of rectangular amulets). This makes learning the hit-box of each type of bullet an important part of the learning process. There are, however, certain exceptions:
Patchouli's "Metal Fatigue" bullets are larger than normal for that type of bullet, greatly screwing up hardcore players that memorize exactly how large they normally are.
Knives have oddly shaped hitboxes that are larger than the sprite. Well, normally larger than the sprite. For some reason, later games have occasionally messed with the sprite to make it more accurate, while leaving the hitbox alone. They're still quite dangerous to players used to bullets having small hitboxes.
Mountain of Faith has Kanako's extremely long oblong bullets during her first Spell Card attack, which appear to have rectangular hitboxes that make them absurdly big around the corners.
In "Imperishable Night", Mokou's "Honest Man's Death" features a laser. The model of this laser forms before its hitbox does, meaning that you have to move into the laser in order not to be killed by it.
Enemies' collision boxes are quite variable, though finding this out tends to be dangerous. While they're normally the same size as the enemies' hitbox, it's been known to get smaller or disappear entirely during patterns that force you to get close.
The classic Resident Evil games on the Playstation has weird hitboxes for zombie dogs; even though they are smaller than the player character, just shooting straight at them is enough to score a hit, even though realistically, you'd have to aim downwards to land a shot. The developers likely made the dog's hitbox larger on purpose for the convenience of the player so that they don't have to worry about making precision aim.
Capital ships in the first Wing Commander have a bit of this going on, when at some angles of attack a ship's sprite doesn't quite match its actual physical model. This can result in blaster fire (or worse, missiles) passing clean through the enemy battleship.
The first two Wing Commanders (and spinoffs based on their engines) in general have a fair amount of this, as they simulated 3D objects flying freely through space by using sprites. The hitboxes are rectangular, no matter what the actual sprite looks like. This is especially noticeable when you are firing at a flat-shaped enemy fighter that is aligned diagonally, and you can hit it at the "empty" corners of the hitbox.
Some mechs in the Mech Warrior series have this issue on certain components. The Uziel in Mechwarrior Living Legends currently has a cockpit hitbox that is physically impossible to damage without splash damage, and many mechs in Mechwarrior 4 have odd hitbox locations, especially on asymmetrical mech. On the Cauldron-Born◊, the "Center Torso" hitbox is actually the projecting cockpit area, the Left Torso is only capable of being hit from the left side, and the Right Torso makes up the entire right side of the mech and can be hit from any angle.
At one point in Heroscape a model's cloak was not considered to be a hitbox. This had to be changed in later sets, as players were abusing the rules by turning their models' cloaked backs to the opponent and claiming they were now immune to fire.
In Warhammer and Warhammer 40000, a model's base is treated as its hitbox for purposes of melee combat, area effects, and such. The result is that, for example, a Gretchin (shrimpy little goblin creature) and a hulking Ork have the same hitbox, and a hitboxes may suddenly change (as when Terminators were moved from 25mm-diameter bases to 40mm-diameter bases).
Previously in 4th edition of 40k, for the purposes of shooting the Model was considered to be a cylinder, as tall as it needed to be for the purposes of being able to be shot at or not (so as long as you see part of the base, you saw the entire model). This was changed with the 5th edition, where True Line of Sight took place and you had to physically see the model in question. This fixed some abusable problems, at the cost of introducing others. Since many players would model their commanders and characters on massively scenic bases, which would make them tall as hell, those commanders were now easy targets. Moreover, the 5th edition introduced fliers, vehicles that are mounted on a massive clear pole on their own bases, which makes getting cover for them incredibly hard*
6th edition fixed by removing a flyer's need for cover; anyone trying to shoot a flyer without dedicated AA weapons gets a huge accuracy penalty
. It also caused the modelling community much headaches, as a lot of aesthetic choices on the modeler's part are now against the rules, as it made the miniature physically smaller (and thus harder to actually hit) while others are being mothballed because they gave the model such height it was impractical to field them now.
Warmachine and Hordes use a similar mechanic than pre-5th edition 40k did, ie. the height of the model is independent of the actual physical model and is determined purely by base size. Models with a smaller base will not block line of sight to models with larger bases. This can lead to some weirdness if you have a model particularly short or tall for it's base size; for example the enormous Behemoth warjack will be completely hidden from line of sight if it hides behind another heavy warjack, despite being almost 50% taller, as they both are on the same size base.
Third Person Shooter
The N64 Mission: Impossible game suffered from a quite disjointed hitbox, especially compared to GoldenEye. However, besides the common cases of bullets that should hit the enemy not having an effect, the biggest problem seemed to be with the individual hitboxes indicating the damage zone. The very common result of aiming anywhere besides the head was: the shot person would be shown flinching, but it wouldn't seem to have a damage effect, and a whole clip of a heavy pistol could be emptied into what seemed to be the lower half their center mass (or arms, legs, etc.), and then they would shoot back unfazed as you were reloading. This was even more jarring when you used what would otherwise be a One-Hit KO dart gun, and was a major contrast to when you shot them in the head with even small handgun and they do a backflip. According to this author, "embarrassing hitbox and bullet detection problems" were a factor in that game.
Skittles adgame Darkened Skye suffered from this in spades. The hitboxes on the enemies and the character's weapon were smaller than the sprites and the character's hitbox was bigger. Leading to hilarious rage-inducing situations when you're flailing away at a little flying lizard and doing no damage at all, while it kills you by clawing at the air a foot and a half away from you.
Neopets released a game that, as part of a plot, was a re-skinned version of an older game. This is notable because the original game sprite was significantly smaller than the re-skinned sprite, but the hitbox remained the same. This was ostensibly a good thing until you realize that the center of the hitbox was located several pixels below the sprite itself, meaning that you had to fly higher than you thought you would to keep from dying. Bear in mind that this game is designed to constantly have your character descend unless you're consciously rising, so there's significantly more danger from scraping the bottom of the screen than the top to begin with.
Non-Video Game Examples:
Live Action TV
Came up as a plot point in an episode of CSI: New York. An Xbox used in a Gears Of War 3 tournament had been hacked to give one player a much smaller hitbox, and everyone else a much bigger one.