charleswiltgen Games
You MUST use this skill for ANY game development, SpriteKit, SceneKit, RealityKit, touch controls, game controller, or interactive simulation work.
Auditors are skills here. Where this router says "Launch
some-auditoragent", 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.
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.
UIRequiresFullScreennow means discrete snap-resizing for games (not a fullscreen opt-out); orientation lock is a preference; minimum size viasizeRestrictions→ 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"];
}
- Building/designing a 2D SpriteKit game? →
skills/spritekit.md - How to use a specific SpriteKit API? →
skills/spritekit-ref.md - SpriteKit broken or performing badly? →
skills/spritekit-diag.md - Adding touch controls, or handling game controller input? →
skills/game-input.md - Maintaining existing SceneKit code? → See axiom-graphics (skills/scenekit.md)
- SceneKit API reference or migration mapping? → See axiom-graphics (skills/scenekit-ref.md)
- Building new 3D game or experience? → See axiom-graphics (skills/realitykit.md)
- How to use a specific RealityKit API? → See axiom-graphics (skills/realitykit-ref.md)
- RealityKit entity not visible, gestures broken, performance? → See axiom-graphics (skills/realitykit-diag.md)
- Migrating SceneKit to RealityKit? → See axiom-graphics (skills/scenekit.md) (migration tree) + See axiom-graphics (skills/scenekit-ref.md) (mapping table)
- Building AR game? → See axiom-graphics (skills/realitykit.md)
- Porting a Mac/Windows game to Apple platforms? → See axiom-graphics (skills/metal-migration.md)
- Unlocking in-game content (asset packs, IAP)? → See axiom-integration (skills/background-assets.md, skills/in-app-purchases.md)
- Game needs fullscreen/orientation lock, or breaks when its window resizes? → See axiom-uikit (skills/uikit-modernization.md)
- Want automated SpriteKit code scan? →
spritekit-auditoragent
Automated Scanning
SpriteKit audit → axiom-audit-spritekit
Detects anti-patterns AND architectural gaps:
- Physics bitmask issues (default
0xFFFFFFFF, missingcontactTestBitMask, magic numbers) - Draw call waste (
SKShapeNodein gameplay, missing texture atlases) - Node accumulation and runaway spawn-in-
update()without cleanup - Action memory leaks (strong
self,.repeatForeverwithoutwithKey:) - Coordinate confusion (
touch.location(in: self.view)instead ofin: self) - Silent input dead zones (custom
touchesBeganwithoutisUserInteractionEnabled) - 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
0xFFFFFFFFcauses phantom collisions) - Camera node pattern for viewport + HUD separation
- SKShapeNode pre-render-to-texture conversion
[weak self]in allSKAction.runclosures- 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
showsNodeCounttrending
Game input (skills/game-input.md):
- One GCController pipeline — touch controls surface as a
GCController, existing logic unchanged TCTouchController.isSupportedgate + 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