FrancoStino/2d-games

2D Game Development

Principles for 2D game systems. Pair with game-development/web-games / game-development/engine-selection for framework choice.

---

Shell vs guest (web)

| Setup | 2D systems live… | |-------|------------------| | Full-screen 2D game | Entire app (Phaser/Kaplay/Pixi/Canvas) | | Hybrid DOM + challenges | Only inside guest viewports; tear down when done |

---

1. Sprite Systems

| Component | Purpose | |-----------|---------| | Atlas | Combine textures, reduce draw calls | | Animation | Frame sequences (often 8-24 FPS) | | Pivot | Rotation/scale origin | | Layering | Z-order control |

Animation Principles

• Squash and stretch for impact
• Anticipation before action
• Follow-through after action

---

2. Tilemap Design

| Factor | Recommendation | |--------|----------------| | Size | 16x16, 32x32, 64x64 | | Auto-tiling | Use for terrain | | Collision | Simplified shapes |

| Layer | Content | |-------|---------| | Background | Non-interactive scenery | | Terrain | Walkable ground | | Props | Interactive objects | | Foreground | Parallax overlay |

---

3. 2D Physics

| Shape | Use Case | |-------|----------| | Box | Rectangular objects | | Circle | Balls, rounded | | Capsule | Characters | | Polygon | Complex shapes |

• Pixel-perfect vs physics-based: pick one approach per game
• Fixed timestep for consistency
• Layers for filtering

---

4. Camera Systems

| Type | Use | |------|-----| | Follow | Track player | | Look-ahead | Anticipate movement | | Multi-target | Two-player | | Room-based | Metroidvania | | Static | Board games, modal skill-checks |

Screen Shake

• Short duration (50-200ms)
• Diminishing intensity
• Use sparingly

---

5. Genre Patterns

Platformer

• Coyote time (leniency after edge)
• Jump buffering
• Variable jump height

Top-down

• 8-directional or free movement
• Aim-based or auto-aim
• Decide whether rotation matters

---

6. Anti-Patterns

| ❌ Don't | ✅ Do | |----------|-------| | Separate textures | Use atlases | | Complex collision shapes | Simplified collision | | Jittery camera | Smooth following | | Pixel-perfect on physics | Choose one approach | | Orphaned RAF/listeners after a guest closes | Full teardown |

---

Remember: 2D is about clarity. Every pixel should communicate.

When to Use

Use for canvas/Phaser/Kaplay/Pixi 2D systems, or guest viewports inside hybrid web apps.

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.