Heads-Up Display

A heads-up display, or HUD, is the information drawn on top of a game's view of the world: health, ammunition, score, lives, a small map, a crosshair, the current objective. The name comes from aviation. Military aircraft began projecting flight data onto a transparent glass in the pilot's line of sight in the decades after the Second World War, so pilots could read speed and altitude without looking down at the instruments.

Games inherited the idea and much of the vocabulary. Early arcade games printed the score and remaining lives at the screen's edge. Later games added health bars, ammunition counters, cooldown timers, quest markers, and a minimap, a small overhead view of the surroundings that shows nearby enemies and exits.

A HUD has to work at a glance, in the middle of action, often in the corner of the eye. Designers rely on a few principles:

• Pre-attentive cues. Color, size, and motion are noticed before anything is read, so a health bar turns red and pulses when low.
• Priority. The most urgent information is largest and nearest the center of attention; see Visual Hierarchy.
• Restraint. Every element competes for attention with the game itself, and too many overwhelm players.
• Context. Many modern HUDs hide elements until they matter, showing ammunition only while aiming.

Some designers move the information into the game world instead. A character's health shown as lights on their armor, ammunition displayed on the weapon itself, or a map the character physically unfolds keeps players looking at the world instead of at overlays; see Diegetic Interface. Horror games favor this approach, since an overlay is a reminder that it's only a game; see Survival Horror. Some games go further and remove the HUD almost entirely, communicating through sound, animation, and the environment.

Removing information has costs. A HUD-free game must teach players to read the world in other ways, through enemy animations, audio cues, and visual signals; see Signifier. Players who rely on clear indicators, including many with impaired vision or hearing, may lose access; good games let players resize, reposition, or toggle elements.

Map markers are a particular debate. Open-world games that place an icon on every point of interest make navigation easy but turn exploration into following arrows; see Open World Design. Some games deliberately give only directions and landmarks, trusting players to find their own way.

The HUD's problems are those of any dashboard that must surface the state of a complex system quickly, and its filling meters are progress bars under another name.