Games

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

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Auditors are skills here. Where this router says "Launch some-auditor agent", invoke the matching Codex skill instead — same procedure, no Claude Code agent required.

Available: axiom-audit-spritekit.

The ones that shell out — builds, tests, simulators, crash symbolication — need shell access to run.

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Quick Reference

Symptom / Task	Reference
Building a SpriteKit game	See skills/spritekit.md
Adding touch controls to a game (TouchController)	See skills/game-input.md
Game controller input (GCController, polling vs handlers)	See skills/game-input.md
Controller Home button settings, spatial accessories OS27	See skills/game-input.md
Game window resizing, orientation lock, UIRequiresFullScreen OS27	See axiom-uikit (skills/uikit-modernization.md)
SpriteKit API lookup	See skills/spritekit-ref.md
Physics contacts not firing	See skills/spritekit-diag.md
Frame rate drops (SpriteKit)	See skills/spritekit-diag.md
Touches not registering	See skills/spritekit-diag.md
Memory spikes in gameplay	See skills/spritekit-diag.md
Coordinate confusion	See skills/spritekit-diag.md
Scene transition crashes	See skills/spritekit-diag.md
Objects tunneling through walls	See skills/spritekit-diag.md
SpriteKit node/action reference	See skills/spritekit-ref.md
SceneKit maintenance/migration	See axiom-graphics (skills/scenekit.md)
SceneKit API / migration mapping	See axiom-graphics (skills/scenekit-ref.md)
RealityKit (3D, ECS, AR)	See axiom-graphics (skills/realitykit.md)
RealityKit API reference	See axiom-graphics (skills/realitykit-ref.md)
RealityKit diagnostics	See axiom-graphics (skills/realitykit-diag.md)
RealityKit 27 game features (navmesh, LOD, splats)	See axiom-graphics (skills/realitykit-ref.md Part 10)
Long-session game performance tracing (metalperftrace)	See axiom-graphics (skills/display-performance.md Part 12)
Porting a Mac/Windows game to Metal	See axiom-graphics (skills/metal-migration.md)
In-game content, asset packs, IAP	See axiom-integration (skills/background-assets.md, skills/in-app-purchases.md)

External Routes

These topics are part of the broader games/3D domain but live in separate skill suites:

SceneKit (3D — soft-deprecated iOS 26):

• Maintenance and migration planning → See axiom-graphics (skills/scenekit.md)
• API reference and migration mapping → See axiom-graphics (skills/scenekit-ref.md)

RealityKit (3D — modern):

• ECS architecture, AR, SwiftUI integration → See axiom-graphics (skills/realitykit.md)
• API reference → See axiom-graphics (skills/realitykit-ref.md)
• Troubleshooting → See axiom-graphics (skills/realitykit-diag.md)
• 27-cycle game-engine layer: navigation mesh + pathfinding, behavior trees, animation graphs, LOD, Gaussian splats → See axiom-graphics (skills/realitykit-ref.md Part 10)

Game performance and porting:

• Long-session game traces, metalperftrace CLI, Game Performance Overview template → See axiom-graphics (skills/display-performance.md Part 12)
• Metal migration, shader conversion → See axiom-graphics (skills/metal-migration.md)

In-game content and monetization:

• Apple-Hosted Background Assets, asset packs, Steam depot conversion → See axiom-integration (skills/background-assets.md)
• In-app purchase, StoreKit views → See axiom-integration (skills/in-app-purchases.md)

Windowing and orientation (OS27):

• Every app resizes at 27, iPhone included. UIRequiresFullScreen now means discrete snap-resizing for games (not a fullscreen opt-out); orientation lock is a preference; minimum size via sizeRestrictions → See axiom-uikit (skills/uikit-modernization.md)
• Game runs in iPhone Mirroring: trackpad/mouse input reaches custom gestures as indirect events, and the scene always reports portrait → See axiom-uikit (skills/uikit-modernization.md)
• Metal drawable sizing, render-target reallocation, and quality throttling during live resize → See axiom-graphics (skills/resizable-rendering.md)

Decision Tree

digraph games {
    start [label="Game development" shape=ellipse];
    what [label="Which framework?" shape=diamond];
    sprite_what [label="SpriteKit need?" shape=diamond];

    start -> what;
    what -> sprite_what [label="SpriteKit (2D)"];
    what -> "skills/game-input.md" [label="touch controls / game controllers"];
    what -> "axiom-graphics/scenekit" [label="SceneKit (3D legacy)"];
    what -> "axiom-graphics/realitykit" [label="RealityKit (3D modern)"];
    what -> "axiom-graphics/metal-migration" [label="porting (Metal)"];

    sprite_what -> "skills/spritekit.md" [label="architecture/patterns"];
    sprite_what -> "skills/spritekit-ref.md" [label="API lookup"];
    sprite_what -> "skills/spritekit-diag.md" [label="broken/slow"];
}

1. Building/designing a 2D SpriteKit game? → skills/spritekit.md
2. How to use a specific SpriteKit API? → skills/spritekit-ref.md
3. SpriteKit broken or performing badly? → skills/spritekit-diag.md
4. Adding touch controls, or handling game controller input? → skills/game-input.md
5. Maintaining existing SceneKit code? → See axiom-graphics (skills/scenekit.md)
6. SceneKit API reference or migration mapping? → See axiom-graphics (skills/scenekit-ref.md)
7. Building new 3D game or experience? → See axiom-graphics (skills/realitykit.md)
8. How to use a specific RealityKit API? → See axiom-graphics (skills/realitykit-ref.md)
9. RealityKit entity not visible, gestures broken, performance? → See axiom-graphics (skills/realitykit-diag.md)
10. Migrating SceneKit to RealityKit? → See axiom-graphics (skills/scenekit.md) (migration tree) + See axiom-graphics (skills/scenekit-ref.md) (mapping table)
11. Building AR game? → See axiom-graphics (skills/realitykit.md)
12. Porting a Mac/Windows game to Apple platforms? → See axiom-graphics (skills/metal-migration.md)
13. Unlocking in-game content (asset packs, IAP)? → See axiom-integration (skills/background-assets.md, skills/in-app-purchases.md)
14. Game needs fullscreen/orientation lock, or breaks when its window resizes? → See axiom-uikit (skills/uikit-modernization.md)
15. Want automated SpriteKit code scan? → spritekit-auditor agent

Automated Scanning

SpriteKit audit → axiom-audit-spritekit

Detects anti-patterns AND architectural gaps:

• Physics bitmask issues (default 0xFFFFFFFF, missing contactTestBitMask, magic numbers)
• Draw call waste (SKShapeNode in gameplay, missing texture atlases)
• Node accumulation and runaway spawn-in-update() without cleanup
• Action memory leaks (strong self, .repeatForever without withKey:)
• Coordinate confusion (touch.location(in: self.view) instead of in: self)
• Silent input dead zones (custom touchesBegan without isUserInteractionEnabled)
• Missing object pooling for hot spawns
• Missing/ungated debug overlays
• Leaked scenes (transition without removeAllActions() and child cleanup)
• Missing time-step clamping → spiral-of-death teleports bodies through walls
• HUD attached to scene root instead of camera (drifts with scrolling)
• Fast bodies without usesPreciseCollisionDetection (tunneling)

Scores: PERFORMANT / DEGRADED / UNPLAYABLE

Critical Patterns

SpriteKit (skills/spritekit.md):

• 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

SpriteKit diagnostics (skills/spritekit-diag.md):

• 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

Game input (skills/game-input.md):

• One GCController pipeline — touch controls surface as a GCController, existing logic unchanged
• TCTouchController.isSupported gate + connect/render/touch-routing setup
• Half-screen collider shapes for movement and camera (never small circles)
• Safe-area-adjusted anchor offsets for fullscreen games
• GCMouse delta look/aim + GCKeyboard key state (iPad pointer, iPhone Mirroring)
• Controller Home button settings + visionOS spatial accessories OS27

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. spritekit.md 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. spritekit-diag.md Symptom 6 resolves in 5 min.
"Physics is straightforward"	Three different bitmask properties, modification rules inside callbacks, and tunneling edge cases. spritekit.md Section 3 covers all gotchas.
"The performance is fine on my device"	Performance varies dramatically across devices. spritekit.md 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-graphics (skills/scenekit.md) has the migration decision tree.
"ECS is overkill for a simple 3D app"	You're already using ECS — Entity + ModelComponent. axiom-graphics (skills/realitykit.md) shows how to scale from simple to complex.
"I don't need collision shapes for taps"	RealityKit gestures require CollisionComponent. axiom-graphics (skills/realitykit-diag.md) diagnoses this in 2 min vs 30 min guessing.
"I'll overlay UIButtons for touch controls"	TouchController renders in your Metal pass and surfaces as a GCController — existing controller logic just works. UIButton overlays mean a second input path and per-frame UIKit cost. game-input.md Section 2.
"Touch controls = put every controller button on screen"	A 1:1 mapping clutters the play area and demands 3+ fingers. game-input.md Section 5 has the redesign patterns (context icons, hide unused, collapse combos).
"Games are fullscreen — resizability doesn't apply to me"	At 27 every app resizes, iPhone included. UIRequiresFullScreen only gets a game discrete snap-resizing, not a fixed canvas. axiom-uikit (skills/uikit-modernization.md) has the scene-geometry and minimum-size patterns.

Example Invocations

User: "I'm building a SpriteKit game" → See skills/spritekit.md

User: "My physics contacts aren't firing" → See skills/spritekit-diag.md

User: "How do I create a physics body from a texture?" → See skills/spritekit-ref.md

User: "Frame rate is dropping in my game" → See skills/spritekit-diag.md

User: "What action types are available?" → See skills/spritekit-ref.md

User: "Objects pass through walls" → See skills/spritekit-diag.md

User: "I'm porting my controller game to iPhone and need touch controls" → See skills/game-input.md

User: "How do I handle game controller input?" → See skills/game-input.md

User: "How do I read spatial accessory input on visionOS?" → See skills/game-input.md

User: "My game's layout breaks when the window is resized" → See axiom-uikit (skills/uikit-modernization.md)

User: "I need to build a 3D game" → Invoke: See axiom-graphics (skills/realitykit.md)

User: "I'm migrating from SceneKit to RealityKit" → Invoke: See axiom-graphics (skills/scenekit.md) + See axiom-graphics (skills/scenekit-ref.md)

User: "Can you scan my SpriteKit code for common issues?" → axiom-audit-spritekit