Unity Game Builder

Production-grade Unity 6 (and 2023 LTS) guidance for shipping real games, not prototypes. This skill knows the modern stack — DOTS/ECS, Addressables, the new Input System, URP, and Cinemachine — and the platform quirks of building for iOS, Android, and Steam. It's aimed at C# developers who already know Unity basics but want correct, performant patterns instead of tutorial-grade Update() spaghetti.

When to use it

• You're profiling a scene that drops below 60 FPS on a mid-tier Android phone and need to move hot logic into Burst-compiled jobs or ECS systems.
• You're replacing Resources.Load with Addressables and need correct group layout, label-based loading, and a Remote Content CDN pipeline.
• You're wiring PlayerInput / Input Actions and want a clean action-map setup that survives gamepad + touch + keyboard.
• You're tuning URP for mobile (Forward vs Forward+, MSAA, render scale) or chasing a build that won't pass App Store / Play Console review.

How it works

The skill applies concrete APIs and project conventions:

• DOTS/ECS: IComponentData, ISystem with [BurstCompile], SystemAPI.Query, IJobEntity, and EntityCommandBuffer for structural changes. Knows the Entities, Burst, and Collections packages and when not to use ECS (small entity counts, heavy GameObject interop).
• Addressables: AddressableAssetSettings groups, Addressables.LoadAssetAsync<T>, LoadSceneAsync, release with Addressables.Release, and addressables_content_state.bin for content updates.
• Input System: .inputactions assets, generated C# wrappers, and the PlayerInput component with action callbacks.
• URP: the UniversalRenderPipelineAsset, Renderer Features, and quality tiers per platform.
• Cinemachine: CinemachineCamera (CM3), virtual camera blends, and CinemachineBrain.
• Build pipeline: BuildPipeline.BuildPlayer / batchmode CI, IL2CPP, and per-platform PlayerSettings.

Example

curl -fsSL --create-dirs -o ~/.claude/skills/unity-game-builder/SKILL.md https://claudeskil.com/skills/unity-game-builder/SKILL.md

[BurstCompile]
public partial struct MoveSystem : ISystem
{
    public void OnUpdate(ref SystemState state)
    {
        float dt = SystemAPI.Time.DeltaTime;
        foreach (var (xf, vel) in
                 SystemAPI.Query<RefRW<LocalTransform>, RefRO<Velocity>>())
            xf.ValueRW.Position += vel.ValueRO.Value * dt;
    }
}

CI build, no editor UI:

Unity -batchmode -quit -projectPath . \
  -executeMethod BuildScript.PerformAndroidBuild -logFile -

Tips & gotchas

• Burst won't compile managed types or try/catch — keep job code to blittable structs and NativeArray/NativeList.
• Structural changes (add/remove components, instantiate) inside a query throw; defer them through an EntityCommandBuffer.
• IL2CPP strips unused code — guard reflection/JSON types with a link.xml or [Preserve].
• On URP mobile, default MSAA + HDR can double bandwidth; disable HDR unless you actually need it.

FAQ

Do I have to convert my whole project to ECS? No. Hybrid is normal — push only the high-count, perf-critical systems (crowds, projectiles, simulation) to ECS and keep UI and gameplay glue as GameObjects.

Does this cover iOS signing? It covers the Unity-side export and PlayerSettings; the generated Xcode project still needs your provisioning profile and signing in Xcode or Fastlane.

Unity 6 or 2023 LTS? Both. Patterns target Unity 6, with notes where 2023 LTS API names differ (e.g. Cinemachine 2 vs 3 component names).