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+# Sonic Universe Theme
+
+Sonic the Hedgehog universe theme. Cinematic, photorealistic visual style — movie-poster quality renders with dramatic lighting, detailed textures, and dynamic compositions.
+
+## Visual Style
+
+- **Cinematic photorealistic** — like Sonic movie posters / Unreal Engine 5 renders
+- Dramatic lighting, volumetric effects, detailed fur/quill textures
+- Characters should feel alive and dimensional, not flat or cartoon-like
+- White or transparent backgrounds for standalone assets
+- Concept sketches stored in `sketches/` subfolders during exploration phase
+
+## Character Roster
+
+### Heroes
+
+| Character | File | Description | Status |
+|-----------|------|-------------|--------|
+| Sonic | `sonic.png` | Blue hedgehog, super speed, iconic quills | Sketch |
+| Shadow | `shadow.png` | Black/red hedgehog, chaos energy, rival | Sketch |
+| Tails | `tails.png` | Two-tailed fox, flight, tech genius | Sketch |
+| Knuckles | `knuckles.png` | Red echidna, super strength, guardian | Sketch |
+| Amy Rose | `amy.png` | Pink hedgehog, Piko Piko Hammer | Sketch |
+| Silver | `silver.png` | Silver-white hedgehog, psychokinesis, futuristic | Sketch |
+| Cream | `cream.png` | Cream rabbit with Chao companion Cheese | Sketch |
+
+### Villains / Anti-heroes
+
+| Character | File | Description | Status |
+|-----------|------|-------------|--------|
+| Dr. Eggman | `eggman.png` | Main villain, genius inventor, red military jacket | Sketch |
+| Metal Sonic | `metal-sonic.png` | Robot hedgehog, blue chrome, red eyes | Sketch |
+| Rouge | `rouge.png` | White bat spy, jewel hunter, bat wings | Sketch |
+| Chaos | `chaos.png` | Translucent water creature, green glowing brain | Sketch |
+| Zavok | `zavok.png` | Red demon, leader of Deadly Six, muscular | Sketch |
+| Infinite | `infinite.png` | Black jackal, silver mask, phantom ruby | Sketch |
+| Egg Robo | `egg-robo.png` | Egg-shaped robot soldier, red/silver metal | Sketch |
+
+## Items
+
+| Item | Description | Status |
+|------|-------------|--------|
+| Chaos Emeralds | 7 colored crystals of immense power | Planned |
+| Gold Rings | Collectible rings, life energy | Planned |
+| More TBD | — | — |
+
+## Asset Inventory
+
+| Category | Path | Count | Description |
+|----------|------|-------|-------------|
+| Protagonist sketches | `sketches/protagonists/` | 7 | Cinematic concept sketches of heroes |
+| Antagonist sketches | `sketches/antagonists/` | 7 | Cinematic concept sketches of villains |
+
+## Usage in Templates
+
+All paths relative to project root:
+- HTML templates: `/assets/themes/sonic/{category}/{file}`
+- Generator scripts (from docs/): `../../assets/themes/sonic/{category}/{file}`
+- Generator scripts (from project root): `assets/themes/sonic/{category}/{file}`
+
+## Color Palette
+
+TBD — will be defined after initial sketches are reviewed and art direction is confirmed.
+
+## Reference Policy
+
+- `heroes/` — use existing hero images as `--ref` for consistency within character
+- `items/` — use existing items as `--ref` within same item type
+- Cross-character refs: use any hero sketch to maintain style consistency
+
+## Adding New Assets
+
+1. Generate via `/gen-image` with cinematic photorealistic style keywords
+2. Save sketches/concepts to `{category}/sketches/`
+3. Final production assets go directly to `{category}/`
+4. Use `--ref` from same category for visual consistency
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