iOS Games Router

You MUST use this skill for ANY game development, SpriteKit, SceneKit, RealityKit, or interactive simulation work.

When to Use

Use this router when:

• Building a new SpriteKit game or prototype (2D)
• Building a 3D game with SceneKit or RealityKit
• Implementing physics (collisions, contacts, forces, joints)
• Setting up game architecture (scenes, layers, cameras, ECS)
• Debugging SpriteKit, SceneKit, or RealityKit issues
• Optimizing game performance (draw calls, node counts, entity counts, batching)
• Managing game loop, delta time, or pause handling
• Implementing touch/input handling in a game context
• Integrating SpriteKit or RealityKit with SwiftUI
• Working with particle effects, texture atlases, or 3D models
• Looking up SpriteKit, SceneKit, or RealityKit API details
• Migrating from SceneKit to RealityKit
• Building AR games with RealityKit

Routing Logic

SpriteKit (2D)

Architecture, patterns, and best practices → /skill axiom-spritekit

• Scene graph model, coordinate systems, anchor points
• Physics engine: bitmask discipline, contact detection, body types
• Actions system: sequencing, grouping, named actions, timing
• Input handling: touches, coordinate conversion
• Performance: draw calls, batching, object pooling, SKShapeNode trap
• Game loop: frame cycle, delta time, pause handling
• Scene transitions and data passing
• SwiftUI integration (SpriteView, UIViewRepresentable)
• Metal integration (SKRenderer)
• Anti-patterns and code review checklist
• Pressure scenarios with push-back templates

API reference and lookup → /skill axiom-spritekit-ref

• All 16 node types with properties and performance notes
• SKPhysicsBody creation methods and properties
• Complete SKAction catalog (movement, rotation, scaling, fading, composition, physics)
• Texture and atlas management
• SKConstraint types and SKRange
• SKView configuration and scale modes
• SKEmitterNode properties and presets
• SKRenderer setup and SKShader syntax

Troubleshooting and diagnostics → /skill axiom-spritekit-diag

• Physics contacts not firing (6-branch decision tree)
• Objects tunneling through walls (5-branch)
• Poor frame rate (4 top branches, 12 leaves)
• Touches not registering (6-branch)
• Memory spikes and crashes (5-branch)
• Coordinate confusion (5-branch)
• Scene transition crashes (5-branch)

Automated scanning → Launch spritekit-auditor agent or /axiom:audit spritekit (physics bitmasks, draw call waste, node accumulation, action memory leaks, coordinate confusion, touch handling, missing object pooling, missing debug overlays)

SceneKit (3D — Deprecated)

SceneKit is soft-deprecated as of iOS 26. Use for maintenance of existing code only. New 3D projects should use RealityKit.

Maintenance and migration planning → /skill axiom-scenekit

• Scene graph architecture, coordinate system, transforms
• Rendering: SCNView, SceneView (deprecated), SCNViewRepresentable
• Geometry, PBR materials, shader modifiers
• Lighting, animation (SCNAction, SCNTransaction, CAAnimation bridge)
• Physics: bodies, collision categories, contact delegate
• Asset pipeline: Model I/O, USD/DAE/SCN formats
• ARKit integration (legacy ARSCNView)
• Migration decision tree (when to migrate vs maintain)
• Anti-patterns and pressure scenarios

API reference and migration mapping → /skill axiom-scenekit-ref

• Complete SceneKit → RealityKit concept mapping table
• Scene graph API: SCNScene, SCNNode, SCNGeometry
• Materials: lighting models, PBR properties, shader modifiers
• Lighting: all light types with properties
• Camera: SCNCamera properties
• Physics: body types, shapes, joints
• Animation: SCNAction catalog, timing functions
• Constraints: all constraint types

RealityKit (3D — Modern)

For non-game 3D content display (product viewers, AR try-on, spatial computing), the ios-graphics router also routes to these RealityKit skills.

Architecture, ECS, and best practices → /skill axiom-realitykit

• Entity-Component-System mental model and paradigm shift
• Entity hierarchy, transforms, world-space queries
• Built-in and custom components, component lifecycle
• System protocol, update ordering, event handling
• SwiftUI integration: RealityView, Model3D, attachments
• AR on iOS: AnchorEntity types, SpatialTrackingSession
• Interaction: ManipulationComponent, gestures, hit testing
• Materials: SimpleMaterial, PBR, Unlit, Occlusion, ShaderGraph, Custom
• Physics: collision shapes, groups/filters, events, forces
• Animation: transform, USD playback, playback control
• Audio: spatial, ambient, channel
• Performance: instancing, component churn, shape optimization
• Multiplayer: synchronization, ownership
• Anti-patterns and code review checklist
• Pressure scenarios

API reference and lookup → /skill axiom-realitykit-ref

• Entity API: properties, hierarchy, subclasses
• Complete component catalog with all properties
• MeshResource generators
• ShapeResource types and performance
• System protocol and EntityQuery
• Scene events catalog
• RealityView API: initializers, content, gestures
• Model3D API
• Material system: all types with full property listings
• Animation timing functions and playback control
• Audio components and playback
• RealityRenderer (Metal integration)

Troubleshooting and diagnostics → /skill axiom-realitykit-diag

• Entity not visible (8-branch decision tree)
• Anchor not tracking (6-branch)
• Gesture not responding (6-branch)
• Performance problems (7-branch)
• Material looks wrong (6-branch)
• Physics not working (6-branch)
• Multiplayer sync issues (5-branch)

Decision Tree

1. Building/designing a 2D SpriteKit game? → axiom-spritekit
2. How to use a specific SpriteKit API? → axiom-spritekit-ref
3. SpriteKit broken or performing badly? → axiom-spritekit-diag
4. Maintaining existing SceneKit code? → axiom-scenekit
5. SceneKit API reference or migration mapping? → axiom-scenekit-ref
6. Building new 3D game or experience? → axiom-realitykit
7. How to use a specific RealityKit API? → axiom-realitykit-ref
8. RealityKit entity not visible, gestures broken, performance? → axiom-realitykit-diag
9. Migrating SceneKit to RealityKit? → axiom-scenekit (migration tree) + axiom-scenekit-ref (mapping table)
10. Building AR game? → axiom-realitykit
11. Physics contacts not working (SpriteKit)? → axiom-spritekit-diag (Symptom 1)
12. Frame rate dropping (SpriteKit)? → axiom-spritekit-diag (Symptom 3)
13. Coordinate/position confusion (SpriteKit)? → axiom-spritekit-diag (Symptom 6)
14. Need the complete action list? → axiom-spritekit-ref (Part 3)
15. Physics body setup reference? → axiom-spritekit-ref (Part 2)
16. Entity not visible (RealityKit)? → axiom-realitykit-diag (Symptom 1)
17. Gesture not responding (RealityKit)? → axiom-realitykit-diag (Symptom 3)
18. Want automated SpriteKit code scan? → spritekit-auditor (Agent)

Anti-Rationalization

Thought	Reality
"SpriteKit is simple, I don't need a skill"	Physics bitmasks default to 0xFFFFFFFF and cause phantom collisions. The bitmask checklist catches this in 2 min.
"I'll just use SKShapeNode, it's quick"	Each SKShapeNode is a separate draw call. 50 of them = 50 draw calls. axiom-spritekit has the pre-render-to-texture pattern.
"I can figure out the coordinate system"	SpriteKit uses bottom-left origin (opposite of UIKit). Anchor points add another layer. axiom-spritekit-diag Symptom 6 resolves in 5 min.
"Physics is straightforward"	Three different bitmask properties, modification rules inside callbacks, and tunneling edge cases. axiom-spritekit Section 3 covers all gotchas.
"The performance is fine on my device"	Performance varies dramatically across devices. axiom-spritekit Section 6 has the debug overlay checklist.
"SceneKit is fine for our new project"	SceneKit is soft-deprecated iOS 26. No new features, only security patches. axiom-scenekit has the migration decision tree.
"I'll learn RealityKit later"	Every line of SceneKit is migration debt. axiom-scenekit-ref has the concept mapping table so the transition is concrete, not abstract.
"ECS is overkill for a simple 3D app"	You're already using ECS — Entity + ModelComponent. axiom-realitykit shows how to scale from simple to complex.
"I don't need collision shapes for taps"	RealityKit gestures require CollisionComponent. axiom-realitykit-diag diagnoses this in 2 min vs 30 min guessing.
"I'll just use a Timer for game updates"	Timer-based updates miss frames and aren't synchronized with rendering. axiom-realitykit has the System pattern.

Critical Patterns

axiom-spritekit:

• PhysicsCategory struct with explicit bitmasks (default 0xFFFFFFFF causes phantom collisions)
• Camera node pattern for viewport + HUD separation
• SKShapeNode pre-render-to-texture conversion
• [weak self] in all SKAction.run closures
• Delta time with spiral-of-death clamping

axiom-spritekit-ref:

• Complete node type table (16 types with batching behavior)
• Physics body creation methods (circle cheapest, texture most expensive)
• Full action catalog with composition patterns
• SKView debug overlays and scale mode matrix

axiom-spritekit-diag:

• 5-step bitmask checklist (2 min vs 30-120 min guessing)
• Debug overlays as mandatory first diagnostic step
• Tunneling prevention flowchart
• Memory growth diagnosis via showsNodeCount trending

axiom-scenekit:

• Migration decision tree (new project → RealityKit, existing → maintain or migrate)
• USDZ asset conversion before migration (xcrun scntool)
• SceneView deprecation and SCNViewRepresentable replacement
• Pressure scenarios for "just use SceneKit" rationalization

axiom-scenekit-ref:

• Complete SceneKit → RealityKit concept mapping table
• All material lighting models and properties
• Full constraint catalog

axiom-realitykit:

• ECS mental shift table (scene graph thinking → ECS thinking)
• Custom component registration (registerComponent())
• Read-modify-write pattern for component updates
• CollisionComponent required for all interaction
• System-based updates instead of timers

axiom-realitykit-ref:

• Complete component catalog with all properties
• MeshResource generators and ShapeResource types
• Scene events catalog
• Material system with all PBR properties

axiom-realitykit-diag:

• Entity visibility checklist (8 branches, 2-5 min vs 30-60 min)
• Gesture debugging (CollisionComponent first check)
• Performance diagnosis (entity count, resource sharing, component churn)
• Physics constraint: entities must share an anchor

Example Invocations

User: "I'm building a SpriteKit game" → Invoke: /skill axiom-spritekit

User: "My physics contacts aren't firing" → Invoke: /skill axiom-spritekit-diag

User: "How do I create a physics body from a texture?" → Invoke: /skill axiom-spritekit-ref

User: "Frame rate is dropping in my game" → Invoke: /skill axiom-spritekit-diag

User: "How do I set up SpriteKit with SwiftUI?" → Invoke: /skill axiom-spritekit

User: "What action types are available?" → Invoke: /skill axiom-spritekit-ref

User: "Objects pass through walls" → Invoke: /skill axiom-spritekit-diag

User: "I need to build a 3D game" → Invoke: /skill axiom-realitykit

User: "How do I add a 3D model to my SwiftUI app?" → Invoke: /skill axiom-realitykit

User: "My RealityKit entity isn't showing up" → Invoke: /skill axiom-realitykit-diag

User: "How do I set up physics in RealityKit?" → Invoke: /skill axiom-realitykit-ref

User: "I'm migrating from SceneKit to RealityKit" → Invoke: /skill axiom-scenekit + /skill axiom-scenekit-ref

User: "What's the RealityKit equivalent of SCNNode?" → Invoke: /skill axiom-scenekit-ref

User: "Should I use SceneKit for my new 3D project?" → Invoke: /skill axiom-scenekit

User: "Tap gestures don't work on my RealityKit entity" → Invoke: /skill axiom-realitykit-diag

User: "How do I set up ECS in RealityKit?" → Invoke: /skill axiom-realitykit

User: "My AR content isn't tracking" → Invoke: /skill axiom-realitykit-diag

User: "What materials are available in RealityKit?" → Invoke: /skill axiom-realitykit-ref

User: "How do I animate entities in RealityKit?" → Invoke: /skill axiom-realitykit-ref

User: "Memory keeps growing during gameplay" → Invoke: /skill axiom-spritekit-diag

User: "What particle emitter settings should I use for fire?" → Invoke: /skill axiom-spritekit-ref

User: "Can you scan my SpriteKit code for common issues?" → Invoke: spritekit-auditor agent