Game Feel Integrator

Apply juice to gameplay events using the GFD Feedback Matrix.

Before You Start

1. Read docs/ProjectConfig.yaml for:
   • feel_tools.tweening — which tween library ("dotween", "primetween", or "none").
   • feel_tools.feedback_system — feedback framework if any.
   • feel_tools.audio — audio middleware.
   • feel_tools.camera — camera system (Cinemachine, custom, etc.).
   • mcp.unity_mcp — if true, call refresh_unity after creating files.
2. Read docs/GFD.md for the Feedback Matrix — it defines which events need which feedback channels.
3. Read docs/CODING_STANDARDS.md for async patterns (Awaitable + CancellationToken) used in middleware-agnostic patterns.

Rule of Three

Every meaningful action needs feedback in at least 3 channels: Visual, Audio, Kinesthetic.

Middleware Reference

• DOTween: See references/dotween.md
• PrimeTween: See references/primetween.md
• No middleware: Use async Awaitable coroutines
• Shader effects as feel: See references/shaders-as-feel.md — outline flash, dissolve, chromatic aberration, UV scroll, distortion

Theory & Inspiration

• Game feel foundations + Loic Jacob methodology: See references/gamefeel-theory.md

Universal Patterns (middleware-agnostic)

Hitstop

private async Awaitable Hitstop(float duration = 0.05f)
{
    Time.timeScale = 0f;
    await Awaitable.WaitForSecondsAsync(duration);
    Time.timeScale = 1f;
}

Shake Profile

[System.Serializable]
public struct ShakeProfile
{
    public float duration;
    public float magnitude;
    public static ShakeProfile Light => new() { duration = 0.1f, magnitude = 0.1f };
    public static ShakeProfile Medium => new() { duration = 0.2f, magnitude = 0.3f };
    public static ShakeProfile Heavy => new() { duration = 0.35f, magnitude = 0.6f };
}

Object Pooling

Frequently spawned FX (particles, floating text, projectiles) must be pooled to avoid GC spikes:

public class FXPool<T> where T : MonoBehaviour
{
    private readonly Queue<T> _pool = new();
    private readonly T _prefab;
    private readonly Transform _parent;

    public T Get() {
        var item = _pool.Count > 0 ? _pool.Dequeue() : Object.Instantiate(_prefab, _parent);
        item.gameObject.SetActive(true);
        return item;
    }

    public void Return(T item) {
        item.gameObject.SetActive(false);
        _pool.Enqueue(item);
    }
}

Rules: Pool all particles, floating text, projectiles. Return to pool on OnParticleSystemStopped or after tween completes. Pre-warm pools during scene load.

Performance Tips

• Camera separation: Use separate world + UI cameras so post-processing doesn't affect UI
• Shaders over CPU animations: For simple repetitive motion (scrolling, pulsing), prefer shader-based animation — runs parallel on GPU, cheaper than DOTween
• Shared materials enable batching: Use material property blocks to vary parameters without breaking draw call batching
• Legacy Animation for simple UI: For simple UI animations (fade, slide), Legacy Animation clips are more performant than Animator controllers

Tween Cleanup

Tweens must be killed when their target is destroyed or disabled, otherwise they cause null reference exceptions or operate on stale objects.

DOTween:

private void OnDestroy()
{
    transform.DOKill();  // Kill all tweens on this transform
}

PrimeTween:

private void OnDestroy()
{
    Tween.StopAll(this);  // Kill all tweens targeting this object
}

No middleware (Awaitable): Use CancellationToken linked to destroyCancellationToken:

private async Awaitable FlashAsync()
{
    var ct = destroyCancellationToken;
    // Awaitable work — auto-cancels when MonoBehaviour is destroyed
    await Awaitable.WaitForSecondsAsync(0.1f, ct);
}

Tuning

• Start exaggerated, then dial back.
• Always check the GFD Feedback Matrix before implementing.
• Ensure tweens are killed on object destruction (see Tween Cleanup above).
• Sync ADSR across channels: Attack and Release timings must match across Visual, Audio, and Kinesthetic. If the SFX fades over 0.5s, particles and shake damping must also fade over 0.5s.
• Profile feel code: Use Unity Profiler (Timeline view) to check that feel effects don't cause frame drops. Particle bursts, tween cascades, and audio one-shots in the same frame can spike.

Sourcing & Communication

• Cite your sources: When suggesting a feel pattern, name the reference game. Example: "A swap feel inspired by Royal Match's snappy 0.15s tween" or "Celeste's coyote time approach." This helps the user visualize and verify.
• Recommend assets: When VFX, SFX, or art assets are needed, reference docs/ASSET_RESOURCES.md for curated free/paid sources.

After Setup

• Write tests: Use uw-unity-test-runner — test feel parameters (shake profile values, hitstop duration) in EditMode tests.
• Code review: Use uw-code-review to verify Rule of Three and tween cleanup before committing.
• UI animation: Use uw-ui-toolkit-binder for UI Toolkit USS transitions. Use game feel patterns here for effects that go beyond USS (complex sequences, screen flash).
• Debug feel issues: Use uw-unity-debugging if effects aren't triggering or timing feels off.

Rules

• Rule of Three: every meaningful action needs feedback in at least 3 channels (Visual, Audio, Kinesthetic).
• Pool all particles, floating text, and projectiles — never Instantiate in hot paths.
• Kill/stop tweens in OnDestroy or OnDisable to prevent null reference exceptions.
• Sync ADSR across channels — mismatched timing breaks immersion.
• [SerializeField] private for shake profiles, tween durations, and other tuning values.
• All game feel code must live inside an .asmdef.
• If ProjectConfig.yaml -> mcp.unity_mcp is true, call refresh_unity after creating files.