HUD (video gaming)
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In video gaming, the HUD (heads-up display) is the method by which information is visually relayed to the player as part of a game's user interface. It takes its name from the head-up displays used in modern aircraft.
Shown on the HUD 
While the information that is displayed on the HUD depends greatly on the game, there are many features that players recognize across many games. Common features include:
- Health / lives – this might include the player's character and possibly other important characters, such as allies or bosses. Real-time strategy games usually show the health of every unit visible on screen. Also, in many (but not all) first- and third-person shooters, when the player is damaged, the screen (or part of it) flashes briefly (usually in red color, representing blood) and shows arrows or other similar images that point to the direction the threat came from, thus informing the player from which direction the enemies are attacking.
- Time – This may be a timer counting down the time limit of the current turn, level, round, minigame, or mission, the time left until a specific event. Or, it may be a timer counting up to records such as lap times in racing games, or the length of time a player can last in games based on survival. Many HUDS also use time displays to show the in-game time, such as the current time of day or year within the game. Some games may also display the real time.
- Weapons/ammunition – Most action games (first- and third-person shooters in particular) show what weapon is being used, and also how much ammunition is in it. Can show other available weapons, and objects like health packs, radios, etc.
- Capabilities – gameplay options that are often accessible by the player during gameplay, such as available weapons, items, or spells. This can include when the ability will become usable again, such as ammunition, magic points, or some other type of "charge up" timer. Icons and/or text may appear in the HUD to indicate other actions that are only available at certain times or in certain places, to show they are available to perform and which button performs it; for example the text "A – open door" may be displayed, but only when the character is near a door.
- Menus – Menus to exit, change options, delete files, change settings, etc.
- Game progression – the player's current score, money, lap, or level (as in stage or as in experience points). This might also include the character's current task or quest.
- Mini-map – a small map of the area that can act like a radar, showing the terrain, allies and/or enemies, locations like safe houses and shops, streets, etc. (See mini-map for more information.)
- Speedometer – used in most games which feature drivable vehicles. Usually shown only when driving one of these.
- Context-sensitive information – shown only as it becomes important, such as tutorial messages, special one-off abilities, and speech subtitles.
- Reticle / cursor / crosshair – an indication of where the character is aiming or where the mouse pointer is. Pressing a key while pointing at an object or character with the cursor can issue actions like shooting, talking, picking up objects, manipulating switches, using computers, etc.
- Stealthometer – displays the awareness level of enemies to the player's presence (used in stealth games and some first person shooters).
- Compass / Quest Arrow - sometimes found in RPGs and First Person Shooters, they help guide the player toward his or her objective. Sometimes the compass itself might not be a real compass, rather one that points toward the next location or goal.
There are also trends common among genres and platforms. Many online games show player names and a chat text box for talking to the other players. RTS games tend to have complex user interfaces, with context-sensitive panels and a full-overview mini-map with fog of war.
How the HUD is displayed 
Typically this information is represented numerically, with the health level being a number from 0–100 (percent): 100 representing full health and 0 representing no health or death. However, many other methods of visual representation can be used. For instance, certain games employ a "health bar" which empties as the player becomes hurt such as Tekken, Street Fighter, and many others.
Armour levels are also commonly monitored, either through a separate readout, or as part of the health system. For example, Halo series uses one recharging shield bar, acting as the health level. When this is depleted the player can only take a few more hits before death. The same goes in Destroy All Humans!, but in the form of Crypto's shields. Traditionally, games used lives to represent health. Every time the main character was injured he would lose one of his limited lives. Another way to display the life in the HUD is demonstrated in Gears of War, where the characters life is displayed only when he is taking damage, in which case a red cog known as the Crimson Omen appears in the center of the screen. The more visible the Crimson Omen is, the more damage the player has sustained and the closer he is to death. This health system is known as the 'Red Ring' system.
There is also a lot of variance with regards to the display of other information. Some games permanently display all the weapons a character is currently carrying, others rely on a pull up weapon selector. Inventory or storage space may also be permanently overlaid over the screen, or accessed via a menu. Alternatively, only a limited number of items stored in the inventory might be displayed at once, with the rest being rotated into view using the [ and ] keys.
In order to maintain the suspension of disbelief, some games make the HUD look like a real HUD within the context of the game's world. Many first-person vehicle simulation games use this technique, showing instruments and displays that the driver of the vehicle would be expected to see. The displays in the helmet in the first-person adventure game Metroid Prime or Star Wars: Republic Commando also mimic the player's point of view. A similar method is used in Tom Clancy's Ghost Recon Advanced Warfighter and Crysis. In some of these circumstances where the player and character within the game are meant to see the same 'HUD' information, Halo for example, the term HMD (Helmet Mounted Display) would technically be more accurate. This is not to be confused with Head-Up Display.
Some games provide the player with an option to hide part or all of the HUD. This is usually used to create cleaner looking screenshots and videos, which can be essential to producing machinima. Certain games like Pac-Man World and Super Mario Galaxy 2 even keep the HUD elements off-screen without any option. When this method is used, they will only appear when affected. In some games, they can temporarily be displayed all at once with the press of a button. In games where that method is not used, the only way to display them at once is by pausing the game.
In the MechWarrior series of games, the HUD display is slightly different. The armor display is in the lower right corner, with the option of displaying as bars or as a wire-frame diagram of the player's mech. The enemy display is located in the lower-right corner, and is much like the armor display. The radar display was located in the upper-left corner in Mechwarrior 2 and 3, and in the lower center of the screen in Mechwarrior 4. An additional interface, either in the upper-right corner of the screen or slaved to a pop-up menu, allow for control of the player's lancemates or starmates (conceptually similar to wingmen).
In the Mario Kart series published by Nintendo, the HUD changes as the series progresses. The HUD in Super Mario Kart includes the total number of coins, number of karts remaining, the total time that the player has taken during the race, the item window for storing power-ups, and the player's current position which is located on the bottom-right corner of the screen. For Mario Kart 64, the HUD adds some new changes including the course map, the top four karts and the number of laps needed to finish. This stays the same until Mario Kart: Double Dash!!, where the position is now located on the top-left corner and the lap counter on the bottom-left. Also, the speedometer shows how fast the karts go during the race and is located on the bottom-right corner and in addition, it also has a pre-race countdown timer in the center of the screen. When that timer comes up, it tells the player when the race or battle can officially begin. For the handheld installments Mario Kart DS and Mario Kart 7, the touchscreen shows the position table and course map, while the top screen shows the actual race itself. Mario Kart 7 also has a alternate first-person perspective, where the player's steering wheel is used. The position color changes during the races in all of the installments except for Super Mario Kart.
A few games give players extensive control over their HUD, such as customizing position, size, color, and opacity. World of Warcraft is notable for allowing players to significantly modify and enhance the user interface through Lua scripting.
Despite the modern dominance of 3D graphics in games, HUDs are frequently rendered with a 2D look, often using sprites.
Reduction of elements 
Sometimes, for the sake of realism, information normally displayed in the HUD is instead disguised as part of the scenery or part of the vehicle in which the player is traveling. For example, when the player is driving a car that can sustain a certain number of hits, a smoke trail might appear when the car can take only two more hits, fire might appear from the car to indicate that the next hit will be fatal. Wounds and bloodstains may sometimes appear on injured characters who may also limp, stagger, slouch over or breathe heavily to indicate they are injured, a notable example being Resident Evil 2.
In rare cases, no HUD is used at all, leaving the player to interpret the auditory and visual cues in the gameworld. The elimination of elements has hardly become a trend in game development nowadays, but can be witnessed in several titles as of late. Some classic examples of games without HUDs are Silent Hill 2, Jurassic Park: Trespasser, Ico, The Getaway, Fable III, Another World, Mirror's Edge, King Kong (however it can be turned on and off, at the player's will.), Dead Space, Call of Cthulhu: Dark Corners of the Earth, and Resident Evil.
HUDs and burn-in 
Prolonged display of HUD elements on certain CRT-based screens may cause permanent damage in the form of burning into the inner coating of the television sets, which is impossible to repair. Also players who pause their games for long hours without turning off their television or putting it on standby risk harming their TV sets. Plasma TV screens are also at risk, although the effects are usually not as permanent.
- Greg Wilson (2006). "Off With Their HUDs!: Rethinking the Heads-Up Display in Console Game Design". Gamasutra. Retrieved February 14, 2006.