Unity Review

When reviewing Unity C# code, apply the following engine-specific checks.

Per-Frame Allocation

Flag any new allocation inside Update(), FixedUpdate(), LateUpdate(), or coroutine bodies. This includes: new List<T>(), new Vector3() (struct boxing in certain contexts), string concatenation with +, LINQ queries (.Where(), .Select(), .ToList()), lambda captures that allocate closure objects.

Verify reusable buffers are declared as fields, cleared, and refilled each frame. Check for GetComponent<T>() calls in per-frame code — these should be cached in Awake() or Start().

Flag Debug.Log() in per-frame code — strip or guard with #if UNITY_EDITOR.

Object Pooling

Verify frequently spawned objects (enemies, projectiles, effects, drops) use ObjectPool<T> or equivalent. Flag Object.Instantiate() and Object.Destroy() in gameplay code paths. Check that pooled objects reset state completely on return (position, health, velocity, timers, active components).

Verify pool warm-up (pre-instantiation) occurs during loading, not during gameplay. Flag pools with no maximum size cap — unbounded pools can exhaust memory.

FindObject Anti-Patterns

Flag all uses of FindObjectsByType, FindObjectOfType, GameObject.Find, GameObject.FindWithTag in per-frame or frequently-called code. These perform full scene searches. Verify the static registry pattern is used: objects register in OnEnable, unregister in OnDisable, and consumers query the registry.

Physics2D / Physics

Verify Physics2D.autoSyncTransforms is false and Physics2D.reuseCollisionCallbacks is true. Flag PolygonCollider2D on dynamic objects — use CircleCollider2D or BoxCollider2D.

Check Layer Collision Matrix — only layers that need to collide should be enabled. Flag raycasts without distance limits (Physics2D.Raycast without maxDistance). Verify ContactFilter2D is reused rather than created per call.

Flag OnCollisionEnter2D / OnTriggerEnter2D callbacks that allocate or perform expensive logic — these can fire multiple times per physics step.

Coroutine Patterns

Flag yield return new WaitForSeconds() — the new allocates every time. Use cached WaitForSeconds fields. Flag coroutines that run indefinitely without stop conditions. Verify StopCoroutine is called on object disable or destroy to prevent orphaned coroutines.

Check for coroutines used where async/await with UniTask or native C# Task would be cleaner (one-shot async operations vs. frame-by-frame iteration).

UI Performance

Verify raycastTarget is disabled on all non-interactive UI elements (labels, backgrounds, decorative images). Flag unnecessary Canvas rebuilds caused by modifying text or image properties every frame. Check that UI updates are throttled with frame-skip patterns (if (Time.frameCount % N == 0)) for non-critical displays (score, timer, debug HUD).

Flag Canvas.ForceUpdateCanvases() in per-frame code. Verify UI elements that change frequently are on a separate Canvas from static UI to minimize rebuild scope.

SerializeField and Inspector

Verify [SerializeField] private is used instead of public for inspector-exposed fields. Flag public fields that should be private with [SerializeField]. Check for [HideInInspector] on fields that are set programmatically and should not be accidentally edited in the inspector.

Flag [SerializeField] on MonoBehaviour references that are set via GetComponent in code — these create confusing dual assignment paths.

ScriptableObject and Data

Verify game configuration uses ScriptableObject assets or JSON data rather than hardcoded values in MonoBehaviours. Flag magic numbers in gameplay code (damage values, cooldown durations, spawn rates) that should be data-driven.

Check that ScriptableObject instances are not modified at runtime — runtime modifications persist in the editor and corrupt the asset.

Mobile-Specific

Flag texture settings with Read/Write Enabled = true on textures that are not accessed from scripts — this doubles memory usage. Verify sprite atlases are used for UI and gameplay sprites. Check that Application.targetFrameRate is set explicitly (typically 30 or 60 for mobile).

For each finding, report: the script name, the specific Unity pattern violated, and the recommended fix.