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

• Building/designing a 2D SpriteKit game? → axiom-spritekit

• How to use a specific SpriteKit API? → axiom-spritekit-ref

• SpriteKit broken or performing badly? → axiom-spritekit-diag

• Maintaining existing SceneKit code? → axiom-scenekit

• SceneKit API reference or migration mapping? → axiom-scenekit-ref

• Building new 3D game or experience? → axiom-realitykit

• How to use a specific RealityKit API? → axiom-realitykit-ref

• RealityKit entity not visible, gestures broken, performance? → axiom-realitykit-diag

• Migrating SceneKit to RealityKit? → axiom-scenekit (migration tree) + axiom-scenekit-ref (mapping table)

• Building AR game? → axiom-realitykit

• Physics contacts not working (SpriteKit)? → axiom-spritekit-diag (Symptom 1)

• Frame rate dropping (SpriteKit)? → axiom-spritekit-diag (Symptom 3)

• Coordinate/position confusion (SpriteKit)? → axiom-spritekit-diag (Symptom 6)

• Need the complete action list? → axiom-spritekit-ref (Part 3)

• Physics body setup reference? → axiom-spritekit-ref (Part 2)

• Entity not visible (RealityKit)? → axiom-realitykit-diag (Symptom 1)

• Gesture not responding (RealityKit)? → axiom-realitykit-diag (Symptom 3)

• 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