SKILL.md
$27
Philosophy
Procedural circles and rectangles are fast to scaffold, but players can't tell a bat from a zombie. Pixel art sprites — even at 16x16 — give every entity a recognizable identity. The key insight: pixel art IS code. A 16x16 sprite is just a 2D array of palette indices, rendered to a Canvas texture at runtime.
Asset Tiers
Tier
Use for
Source
South Park characters (default for personalities)
Named people / CEO characters
Character library at assets/characters/ (relative to plugin root) — photo heads composited onto cartoon bodies with expression spritesheets
Real images (logos, photos)
Company logos, brand marks when game features a named company
Download to public/assets/ with pixel art fallback
Meme/reference images
Source tweet image_url — embed as background, splash, or texture when it enhances thematic identity
Download to public/assets/
Pixel art (fallback)
Non-personality characters, items, game objects, enemies
Code-only 2D arrays rendered at runtime
South Park characters are the default for named personalities (Altman, Amodei, Musk, Zuckerberg, Nadella, Pichai, Huang, Karpathy, Trump, Biden, Obama). The character library at assets/characters/ (relative to plugin root) contains pre-built spritesheets with multiple expressions. Each spritesheet has frames for: normal (0), happy (1), angry (2), surprised (3). Games load these as Phaser spritesheets and wire expression changes to game events.
Pixel art is the fallback for personality characters not yet in the library and the default for non-personality entities (enemies, items, game objects).
Real logos are preferred for brand identity. When a game features OpenAI, Anthropic, Google, etc., download their logo and use it.
Meme images from the source tweet (image_url in thread.json) should be downloaded and incorporated when they enhance visual identity.
All tiers share the same fallback pattern: if an external asset fails to load, fall back to pixel art.
South Park Character System
See character-pipeline.md for the full South Park character system: character library structure, expression constants, expression wiring pattern, bobblehead body pattern, and building new characters (4-tier fallback from full expression build to generative pixel art).
Pixel Art Rendering System
See pixel-renderer.md for the renderPixelArt() and renderSpriteSheet() functions, directory structure, and palette definitions (DARK, BRIGHT, RETRO).
Integration Pattern
See integration-patterns.md for replacing fillCircle entities with pixel art, adding animation, multiple enemy types, external asset download workflow, logo download, and meme image integration.
Sprite Design Rules
When creating pixel art sprites, follow these rules:
1. Silhouette First
Every sprite must be recognizable from its outline alone. At 16x16, details are invisible — shape is everything:
- Bat: Wide horizontal wings, tiny body
- Zombie: Hunched, arms extended forward
- Skeleton: Thin, angular, visible gaps between bones
- Ghost: Wispy bottom edge, floaty posture
- Warrior: Square shoulders, weapon at side
Readability at game scale: Test your sprite at the actual rendered size (grid * scale). A 12x14 sprite at 3x scale is only 36x42 pixels on screen — fine detail is lost. For items and collectibles below 16x16 grid, use bold geometric silhouettes (diamond, star, circle) rather than trying to draw realistic objects. Use a 2px outline (palette index 1) on all edges for small sprites to ensure they pop against any background. Hostile entities (skulls, bombs) should have a fundamentally different silhouette from collectibles (gems, coins) — size, shape, or aspect ratio should differ so players can distinguish them instantly even in peripheral vision.
2. Two-Tone Minimum
Every sprite needs at least:
- Outline color (palette index 1) — darkest, defines the shape
- Fill color — the character's primary color
- Highlight — a lighter spot for dimensionality (usually top-left)
3. Eyes Tell the Story
At 16x16, eyes are often just 1-2 pixels. Make them high-contrast:
- Red eyes (index 3) = hostile enemy
- White eyes (index 8) = neutral/friendly
- Glowing eyes = magic/supernatural
4. Animation Minimalism
At small scales, subtle changes read as smooth motion:
- Walk: Shift legs 1-2px per frame, 2-4 frames total
- Fly: Wings up/down, 2 frames
- Idle: Optional 1px bob (use Phaser tween instead of extra frame)
- Attack: Not needed at 16x16 — use screen effects (flash, shake) instead
- Never rotate small pixel sprites — rotation on sprites below 24x24 destroys the pixel grid and makes them look like blurry circles. Use vertical bobbing, scale pulses, or frame-based animation instead. Rotation only works well on sprites 32x32+.
5. Palette Discipline
- Every sprite in the game shares the same palette
- Differentiate enemies by which palette colors they use, not by adding new colors
- Bat = purple (index 9), Zombie = green (index 10), Skeleton = white (index 8), Demon = red (index 3)
6. Scale Appropriately
Entity Size
Grid
Scale
Rendered
Screen % (540px)
Tiny (pickups, projectiles)
8x8
3
24x24px
4%
Small (items, collectibles)
12x12
3
36x36px
7%
Medium (enemies, obstacles)
16x16
3
48x48px
9%
Large (boss, vehicle)
24x24 or 32x32
3
72-96px
13-18%
Personality (named character)
32x48
4
128x192px
35%
Character-driven games (games starring named characters, personalities, or mascots): Use the Personality archetype. The main character should dominate the screen (~35% of canvas height). Use caricature proportions — large head (60%+ of sprite height) with exaggerated features, compact body — for maximum personality at any scale. Adjust PLAYER.WIDTH and PLAYER.HEIGHT in Constants.js to match.
When replacing geometric shapes with pixel art, match the rendered sprite size to the entity's WIDTH/HEIGHT in Constants.js. If the Constants values are too small for the art style, increase them — the sprite and the physics body should agree.
Process
When invoked, follow this process:
Step 1: Audit the game
- Read
package.jsonto identify the engine
- Read
src/core/Constants.jsfor entity types, colors, sizes
- Read all entity files to find
generateTexture()orfillCirclecalls
- List every entity that currently uses geometric shapes
Step 2: Plan the sprites and backgrounds
Present a table of planned sprites:
Entity
Type
Grid
Frames
Description
Player
Humanoid
16x16
4 (idle + walk)
Cloaked warrior with golden hair
Bat
Flying
16x16
2 (wings up/down)
Purple bat with red eyes
Zombie
Ground
16x16
2 (shamble)
Green-skinned, arms forward
XP Gem
Item
8x8
1 (static + bob tween)
Golden diamond
Ground
Tile
16x16
3 variants
Dark earth with speckle variations
Gravestone
Decoration
8x12
1
Stone marker with cross
Bones
Decoration
8x6
1
Scattered bone pile
Choose the appropriate palette for the game's theme.
Step 3: Implement
- Create
src/core/PixelRenderer.jswithrenderPixelArt()andrenderSpriteSheet()
- Create
src/sprites/palette.jswith the chosen palette
- Create sprite data files in
src/sprites/— one per entity category
- Create
src/sprites/tiles.jswith background tile variants and decorative elements
- Update entity constructors to use
renderPixelArt()/renderSpriteSheet()instead offillCircle()+generateTexture()
- Create or update the background system to tile pixel art ground and scatter decorations
- Add animations where appropriate (walk cycles, wing flaps)
- Verify physics bodies still align (adjust
setCircle()/setSize()if sprite dimensions changed)
Step 4: Verify
- Run
npm run buildto confirm no errors
- Check that physics colliders still work (sprite size may have changed)
- List all files created and modified
- Suggest running
/game-creator:qa-gameto update visual regression snapshots
Checklist
When adding pixel art to a game, verify:
PixelRenderer.jscreated insrc/core/
- Palette defined in
src/sprites/palette.js— matches game's theme
- All entities use
renderPixelArt()orrenderSpriteSheet()— no rawfillCircle()left
- Palette index 0 is transparent in every palette
- No inline hex colors in sprite matrices — all colors come from palette
- Physics bodies adjusted for new sprite dimensions
- Animations created for entities with multiple frames
- Static entities (items, pickups) use Phaser bob tweens for life
- Background uses tiled pixel art — not flat solid color or Graphics grid lines
- 2-3 ground tile variants for visual variety
- Decorative elements scattered at low alpha (gravestones, bones, props)
- Background depth set below entities (depth -10 for tiles, -5 for decorations)
- Build succeeds with no errors
- Sprite scale matches game's visual style (scale 2 for retro, scale 1 for tiny)