Creating a clean, scalable scene architecture for a 2D game is more than just organizing visuals—it’s about building a system that supports gameplay, UI, effects, and camera logic in a way that’s intuitive and future-proof. In this post, we’ll walk through a layered architecture that separates concerns, supports depth-based gameplay, and keeps your UI crisp and your effects polished.

Whether you’re building a vertical shooter, a platformer, or a retro arcade game, this structure gives you the flexibility to scale without chaos.

🧱 Scene Graph Overview

At the core is root_scene, which contains all visual and logical layers. These layers are organized from background to foreground, with clear roles and transformation rules.

root_scene
├── game_group                            # Camera-controlled gameplay container
│   ├── hidden_group                     # Off-screen/inactive entities (object pooling)
│   ├── background_group                 # Default background layer + depth container
│   │   ├── background_bottom_group      # Farthest background visuals (sky, base)
│   │   ├── background_mid_group         # Parallax mid-layers, distant FX
│   │   ├── background_top_group         # Closest background visuals
│   ├── objects_group                    # Default gameplay layer + depth container
│   │   ├── objects_depth_bottom_group   # Farthest gameplay entities
│   │   ├── objects_depth_mid_group      # Primary gameplay layer (player, pickups)
│   │   ├── objects_depth_top_group      # Foreground gameplay entities
│   ├── foreground_group                 # Foreground visuals + depth container
│   │   ├── foreground_bottom_group      # Farthest foreground elements
│   │   ├── foreground_mid_group         # Mid-range foreground visuals
│   │   ├── foreground_top_group         # Closest foreground overlays
│   ├── visual_fx_group                  # Explosions, particles, transient visuals
│
├── hud_group                            # Score, gauges, indicators (screen-anchored)
├── menu_group                           # Title screen, credits (non-blocking UI)
├── modal_group                          # Pause, game over, dialogs (blocking overlays)
├── debug_group                          # Dev-only overlays, performance HUD
├── screen_fx_group                      # CRT shader, bloom, vignette (post-processing)
  

🧠 Layer Roles & Camera Behavior

Each layer has a defined purpose and relationship with the camera. Gameplay and visual layers move with the camera, while UI and post-processing layers remain fixed or apply globally. Note that background and foreground groups can also be used in menu layers along with menu group.

🧰 API Naming Conventions

To keep things clean and predictable, each layer has dedicated adders and getters. This ensures encapsulation and avoids direct manipulation of scene graph internals.

🔧 Adders

python

add_to_hidden_group(obj)
add_to_background_group(obj)
add_to_background_bottom_group(obj)
add_to_background_mid_group(obj)
add_to_background_top_group(obj)

add_to_objects_group(obj)
add_to_objects_depth_bottom_group(obj)
add_to_objects_depth_mid_group(obj)
add_to_objects_depth_top_group(obj)

add_to_foreground_group(obj)
add_to_foreground_bottom_group(obj)
add_to_foreground_mid_group(obj)
add_to_foreground_top_group(obj)

add_to_visual_fx_group(obj)
add_to_hud_group(obj)
add_to_menu_group(obj)
add_to_modal_group(obj)
add_to_debug_group(obj)
add_to_screen_fx_group(obj)
  

🔍 Getters

python

get_hidden_group()
get_background_group()
get_background_bottom_group()
get_background_mid_group()
get_background_top_group()

get_objects_group()
get_objects_depth_bottom_group()
get_objects_depth_mid_group()
get_objects_depth_top_group()

get_foreground_group()
get_foreground_bottom_group()
get_foreground_mid_group()
get_foreground_top_group()

get_visual_fx_group()
get_hud_group()
get_menu_group()
get_modal_group()
get_debug_group()
get_screen_fx_group()
  

📏 Ownership & Layering Rules

To maintain clarity and prevent misuse, each type of entity has a designated home:

• Gameplay entities → objects_group or one of its depth layers
• Background visuals → background_group or its depth layers
• Foreground visuals → foreground_group or its depth layers
• HUD elements → hud_group
• Menus → menu_group
• Blocking overlays → modal_group
• Debug tools → debug_group only
• Visual effects → visual_fx_group
• Post-processing shaders → screen_fx_group
• Camera transformations → applied only to game_group and its children

🚫 Layering Constraints

To avoid rendering chaos and maintain performance:

• ❌ No toFront() calls in gameplay layers
• ✅ UI systems may adjust local order within their own group
• ✅ Depth layers maintain internal z-ordering

✅ Benefits of This Architecture

• Clear separation of concerns: Each layer has a distinct visual and logical role
• Scalable and maintainable: Easy to audit, extend, and debug
• Camera-friendly: game_group isolates gameplay transformations from UI
• Depth flexibility: objects_group, background_group, and foreground_group support layered interactions
• UI integrity: HUD and modals remain crisp and unaffected by zoom/shake
• Post-processing polish: screen_fx_group applies final visual effects globally

🧪 Final Thoughts

This architecture isn’t just a technical blueprint—it’s a philosophy of clarity. By separating gameplay, background, foreground, UI, and effects into well-defined layers, you empower your team to build faster, debug smarter, and scale confidently.

If you’re working on a game and want help adapting this structure to your engine or genre, I’d love to collaborate. Let’s build something beautiful.