|There is more information available on this subject at Heads-up display on the English Wikipedia.|
The HUD is the main source for information in-game in Halo: Combat Evolved, Halo 2, Halo 3, Halo 3: ODST, Halo: Reach, Halo 4, and Halo 5: Guardians, though the appearance of the HUD has changed dramatically from its predecessors. The sensors augmented into the Spartan's body display the soldier's vital signs, which include a measure of their overall health in the form of bars. Note that this "health bar" has been removed from Halo 2 and Halo 3, with the reason being the insertion of automatic biofoam injectors into the Mark VI armor. In Halo 3, there a slight convex appearance to simulate looking through a real visor. Also, the MJOLNIR shields flare up in a grid-shaped pattern, to simulate the player is taking damage. Additionally, the HUD also reports the strength of the wearer's shields through the energy signatures it emanates. Weapons' heat and ammunition levels, as well as grenade type and count are also detected through sensors placed in the Spartan's gloves. In Halo 2 and 3, the Mark VI armor is able to register two weapons when the Spartan is dual-wielding.
Another notable feature on the HUD is that each type of weapon that the gloves detect has its own unique aiming reticle in relation to the type of ammo that it projects and it's statistics. Even heavy weapons have their own reticles. For example, the open circle reticle on the shotgun tells you that although the shot will land somewhere in the directed area, the distance and position are rather unpredictable. Or the Ghost's reticle tells you that the plasma shots will travel as far as the two dots show, but can drift off left or right a little. The reticle is also compatible with the scope of ranged weapons when installed. However, do remember that it is a reticle that is designed to aid the person in pinpointing where the shot will end up, while an aiming cursor shows exactly where the shot will end up.
The motion sensor is another important feature displayed on the HUD. It can sense and track movement in a 15-meter radius (Halo: CE), a 20-meter radius (Halo 2) and a 25-meter radius (Halo 3). Due to the insertion of IFF tags in UNSC soldiers, the radar can distinguish friend (yellow) from foe (red). Finally, the way point indicators are an on-screen directive that point out important objectives or locations in the Spartan's mission, and are extremely useful, measuring the distance the Spartan is from the objective.
Mjolnir Armor, SPI Armor, and Sangheili Armor
- Main article: Mjolnir Powered Assault Armor
The standard Mjolnir Armor contains the following readouts:
- (1) A meter displaying the user's health (only in Halo: Combat Evolved, Halo: Reach, and Halo 5: Guardians).
- Grenade tracking. (only available on MJOLNIR GEN 2 armor)
- (2) A gauge displaying Shield integrity status. (absent from ODST armor and SPI armor as it has no shields)
- (3) A gauge tracking the quantity of ammunition available for weapons carried.
- (4) A motion sensor. (absent from Halo 3: ODST)
- (5) A counter tracking the number and type of grenades carried.
- (6) A targeting reticle which changes relative to the weapon currently in use.
- (7) Acknowledgment lights from other members of the wearer's team.
- (8) Maps and information uploaded over the wearer's TACCOM (seen only in Halo 3: ODST's VISR Database)--translated to a compass in Halo: Reach.
- (9) Zoom Function.
- Function for using a Fiber Optic Probe. (absent from gameplay)
ODST Armor and Marine Body Armor
The Heads-Up-Display used by UNSC Marine Corps and ODST's is similar to that used by Spartans, displaying weapons and grenades carried by the user and their ammunition, and projecting a targeting reticle to assist aim. However, it is notable for lacking several functions, such as the motion sensor and shield bar, which are unavailable for conventional UNSC personnel, though it does display health information. Additionally, ODST helmets integrate a VISR that improves the user's vision in low light areas, also outlining objects in the immediate area - green outlines are "friendly" units, red outlines are "enemy combatants" and blue outlines are discarded or abandoned equipment and weaponry that can be used. The system can also track data and display tactical information, such as maps and waypoints.
Although the games, novelsg and manuals all refer to a Heads-Up Display (HUD), this is technically an incorrect description of the equipment featured in-universe. By definition, a Heads-Up Display is a fixed unit whereby you must look up in order to see it. For example, the HUD in a fighter jet is mounted to the glareshield and cannot be moved. If the pilot looks to his left or right, he can no longer see the display.
The term HUD originally came from looking 'up' out of the cockpit, as opposed to looking down at the gauges on the instrument panel. The correct in-universe term for the equipment in the Halo games is a Helmet Mounted Display (HUD), or HMD. A display mounted or projected onto a helmet's visor, the result of which being that no matter where the wearer looks, the display will remain in front of his eyes. HMD's have been in military service as early as the late 1970s when the Soviet Union was developing the MiG-29 Fulcrum and are currently starting replacing HUD's in the newest generation of fighter jets, and the new Lockheed Martin F-35 Lightning II does not feature a HUD at all, instead completely relying upon the pilots HMD.
- A more accurate term for an in-universe heads-up display is a helmet mounted display.
- The HUD in Halo 2 is the only one in the trilogy that does not display any kind of information on the direction of the fire when the player is hit. Both Halo: Combat Evolved and Halo 3 show arrows that show the player where the shots came from.
- Halo 2 is the only game in which the shield bar is on top of the motion sensor.
- In Halo 3 and Halo 3: ODST, the HUD seems to resemble the visor shape of the helmet.
- In Halo: Reach, when your shields are down, the word "Warning" will show up in the depleted shield indicator. Also, if your health is below yellow, it will continuously flash.
- In the Halo: Reach campaign, the heads-up display gives the player a brief description of the weapon they are currently using and current equipped armor ability by pressing the Back button. In Halo 4, it shows a brief description of the weapon and the Armor Ability they are currently using.
- In Halo 4, the HUD is fully 3-dimensional, and bobs and weaves with the player's movement. Additionally, portions of the player's helmet can be seen at the edges of the screen if he/she is in a first-person view, but you can't see the edges in Multiplayer.