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title: Game UI fundamentals (diegetic, non-diegetic, spatial, meta) applies_to: [game-ui, hud, game-design] version: 1.0.0 last_updated: 2026-05 stability: stable

Game UI fundamentals

Game UI follows different rules from product UI. Game UI exists while the player is doing something else (playing). It must convey information without breaking immersion, work with controllers / touch / keyboard, and adapt to genre conventions.

This file is the foundation for hud-design.md, menu-systems.md, korean-gaming-conventions.md, and game-accessibility.md.

Four UI categories (Mark Russell taxonomy)

A canonical model for game UI. Every game UI element fits one quadrant:

Spatial (in 3D world) Non-spatial (overlay)
Diegetic (exists in the fiction) Spatial diegetic — Dead Space's hologram health on character's spine Non-spatial diegetic — Far Cry 2's GPS held by the character
Non-diegetic (exists for the player only) Spatial non-diegetic — XCOM movement grid drawn on the world Non-spatial non-diegetic — classic HUD (health bar in corner)

Why this matters

  • Diegetic UI keeps players immersed. The character interacts with it; the player doesn't break frame.
  • Non-diegetic UI is faster + clearer but breaks immersion.
  • Spatial UI is more natural in 3D worlds; non-spatial is more readable.

Most games mix all four. Pick the right tool per element: - Health: typically non-spatial non-diegetic (bar in corner). - Quest waypoint: often spatial non-diegetic (arrow in 3D world). - Inventory: usually non-diegetic menu, but Resident Evil 4's case is a famous diegetic inventory.

Reading distance — TV vs handheld vs mobile

Platform Reading distance Min text size
Mobile (handheld) 30-50cm 14sp
PC monitor 50-100cm 12-14pt
Console (TV, 10-foot UI) 2-4m 28-32pt+
VR headset (visual angle, not distance) per platform spec

10-foot UI (TV gaming) requires bigger fonts than designers expect. PS5 / Xbox UI defaults to 28-32pt for body. Test on actual TV at distance.

For Korean PC bang (PC방) culture: monitors at standard PC distance; designs for desktop monitor distance work.

For Korean mobile gaming (huge market): same as global mobile; readable at 30-50cm.

Genre conventions

Game UI follows genre. Players expect certain UI in certain genres; deviating without reason is friction.

FPS (first-person shooter)

Element Position
Crosshair Center
Health Bottom-left or bottom-right corner
Ammo Bottom-right corner
Mini-map Top-left or top-right corner
Objective Top center
Score / killfeed Right side or bottom-left

Examples: Call of Duty, CS, Valorant.

RPG / MMO

Element Position
Health / mana / stamina Bottom-left (player avatar)
Quick action bars Bottom center (1-9 keys)
Mini-map Top-right
Quest log Right side or top-right
Chat Bottom-left
Target frame Top-center or top-left

Examples: WoW, Lost Ark, Final Fantasy XIV. Korean MMOs (Lineage, MapleStory) inherit this layout heavily.

Mobile gacha / RPG

Element Position
Currencies Top of screen (3-5 of them)
Energy / stamina Top
Battle controls Bottom (large, thumb-reachable)
Skill buttons Right side (thumb zone)
Auto-battle / 2x speed Bottom-right (essential for gacha)
Quest indicators Around character or floating

Examples: 원신 (Genshin), 명일방주 (Arknights), Korean genres like 리니지M, 오딘.

Casual / puzzle

Element Position
Score / lives Top
Pause Top-corner
Power-ups Bottom

Examples: Candy Crush, anipang, 카카오프렌즈게임.

Strategy (RTS / 4X)

Element Position
Mini-map Bottom-left or bottom-right
Resource counters Top
Selected unit panel Bottom-center
Build menu Bottom-right
Tech tree / overlays Modal full-screen

Examples: Starcraft, Civilization. Korean Starcraft heritage means competitive RTS UI culture is strong.

HUD vs menu vs in-world

Type Use
HUD (Heads-Up Display) Always visible during gameplay; status / context
Menu Navigated to; not visible during gameplay
In-world / spatial Embedded in 3D world (waypoints, dialogue bubbles)
Modal interrupt Pauses gameplay (death screen, inventory full)

Avoid putting too much in HUD — visual noise during play. Prefer menus for detailed views.

Information density

Genre HUD density
FPS Low (focus on aim)
Racing Medium (speed, position, lap)
RPG / MMO High (player chose this complexity)
Casual Low (don't overwhelm)
Strategy Very high (resources + units + tech)

For Korean MMORPG (Lost Ark, BDO, Lineage M): players accept very dense HUDs. Western audiences sometimes find these "cluttered."

Visual language

Color coding

Universal: - Red: damage, danger, enemy, low health. - Green: friendly, healthy, success, nature. - Yellow / orange: warning, neutral, special. - Blue: mana, ally, info. - Purple / gold: rare / legendary item rarity.

Korean inversion alert: in stock charts, Korean convention has red=up, blue=down (opposite of Western). But in games, red=damage / blue=mana follows global convention.

Item rarity color tiers (canonical)

Common      → Gray / White
Uncommon    → Green
Rare        → Blue
Epic        → Purple
Legendary   → Orange / Gold
Mythic      → Red / Rainbow

Most games use this. Players read rarity instantly via color. Don't invent your own without good reason.

Iconography

  • Currency icons: gold coin (yellow), gem (purple/blue), special (varies).
  • Stats icons: heart (HP), drop (mana / blood / poison), star (XP), shield (defense).
  • Action icons: standardized across genres (settings = gear, inventory = bag, map = globe).

Icons in games are larger than product UI (24-32px common; 48-64px for action buttons). Mobile especially.

Animation in game UI

Game UI animates more than product UI: - Damage numbers float up + fade. - XP bar fills smoothly (200-400ms ease-out). - Item drops bounce / glow. - Notifications slide in + auto-dismiss. - Skill cooldowns sweep around an icon.

Style depends on genre: - Realistic / cinematic: subtle, fast. - Anime / fantasy: dramatic, longer durations, particle effects. - Casual / cute: bouncy, playful.

See knowledge/motion/principles.md for general motion rules; game UI extends with more dramatic motion.

Audio in game UI

Sound effects are part of UI: - Click: every button press has audio feedback. - Hover (PC / console): subtle hover sound. - Confirmation: positive ding for success, negative buzz for error. - Notifications: distinctive sound per type (level-up vs damage vs achievement).

For VR / immersive games: spatial audio matters even more; sounds should emit from where they appear.

Input methods

Game UI must work with whatever input the platform supports:

Input Constraint
Mouse + keyboard (PC) Pointing precise; many keys available
Controller (console) D-pad / sticks; fewer buttons; needs focus management
Touch (mobile) Direct manipulation; thumb zones; no hover
VR controllers 6DOF pointing; raycast UI; physical gestures

Cross-platform UI

Many modern games ship on PC + console + mobile. UI must adapt:

  • PC: hover affordances, right-click context menus, keyboard shortcuts.
  • Console: focus rings, button prompts ("Press X to open"), tab nav.
  • Mobile: bigger tap targets (44pt+), thumb-zone bottom controls.

Defer to platform conventions. Don't force PC-style mouse-driven UI on console; don't force controller-style on mobile.

Button prompts

Console UI shows controller button icons: - Xbox: A, B, X, Y. - PlayStation: ✕ (X), ◯ (Circle), △ (Triangle), □ (Square). - Switch: A, B, X, Y (different positions from Xbox). - Generic: "Confirm", "Cancel", "Back".

For cross-platform: detect controller type and swap icons. Don't assume Xbox.

State persistence

Game UI persists state across: - Sessions (settings, progress). - Death + respawn (HUD state, current target). - Match transitions (lobby → game → results).

Save state at meaningful checkpoints. Lose-progress-on-crash is the worst game UX.

Korean game market notes

(Detail in korean-gaming-conventions.md.)

Quick context: - Mobile gacha + MMO dominate Korean revenue. - PC bang (PC방) culture: PCs at low/free hourly rates; competitive games dominant. - Major studios: NEXON (메이플스토리, FIFA Online), NCSoft (리니지, 길드워), Krafton (배틀그라운드 / PUBG), Smilegate (크로스파이어, 로스트아크), Pearl Abyss (검은사막). - Mobile-first audience: heavy auto-battle, gacha, daily login rewards.

Accessibility intro

(Detail in game-accessibility.md.)

Game UI accessibility: - Subtitles + closed captions (always option). - Color-blind modes (color-coding redundant with shape / pattern). - Remappable controls. - Adjustable text size + UI scale. - High-contrast mode. - Reduced motion option.

2024+: accessibility is increasingly expected; Last of Us Part II / Forza Horizon raised the bar.

Don't

  • Don't break genre conventions without strong reason. Players expect HP bottom-left in MMOs.
  • Don't ignore platform conventions (PC vs console vs mobile have different defaults).
  • Don't make HUD so dense it competes with gameplay attention.
  • Don't skip button prompts on console.
  • Don't use only color to encode meaning (color-blind exclusion).
  • Don't auto-advance dialogue. Player controls the pace.
  • Don't lock UI to one resolution. Scale for different screens.
  • Don't forget audio. Game UI is auditory + visual.

Cross-reference