diff --git a/Assets/Scripts/Mechanics/GameOptimizer.cs b/Assets/Scripts/Mechanics/GameOptimizer.cs
index 32d5b70..9541234 100644
--- a/Assets/Scripts/Mechanics/GameOptimizer.cs
+++ b/Assets/Scripts/Mechanics/GameOptimizer.cs
@@ -31,6 +31,8 @@ namespace Platformer.Mechanics
         [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.AfterSceneLoad)]
         static void SetupJumpThroughPlatforms()
         {
+            // BT5-Dev #28 — Tilemap 영역 포함 모든 일반 Collider Layer 8 변환.
+            // Drop-Through 표준 패턴 = 모든 발판·지면이 Layer 8. PlatformDropThrough Raycast가 하강 시 충돌 활성 = 착지.
             int applied = 0, excluded = 0;
             var allColliders = Object.FindObjectsByType<Collider2D>(FindObjectsSortMode.None);
             var appliedNames = new System.Collections.Generic.List<string>();
@@ -38,7 +40,6 @@ namespace Platformer.Mechanics
             {
                 if (c == null) continue;
                 if (c.isTrigger) { excluded++; continue; }
-                if (c.GetComponent<UnityEngine.Tilemaps.TilemapCollider2D>() != null) { excluded++; continue; }
                 if (c.GetComponent<PlayerController>() != null
                     || c.GetComponent<EnemyController>() != null
                     || c.GetComponent<DeathZone>() != null
@@ -50,18 +51,18 @@ namespace Platformer.Mechanics
                     continue;
                 }
 
-                // PlatformEffector2D 잔존 영역 제거 (BT25 누적 영향 차단)
+                // PlatformEffector2D 잔존 제거 (BT25 누적 영향 차단)
                 var effector = c.GetComponent<PlatformEffector2D>();
                 if (effector != null) Object.Destroy(effector);
                 c.usedByEffector = false;
 
-                // Layer 8 변환 → IgnoreLayerCollision로 기본 통과
+                // Layer 8 변환 → IgnoreLayerCollision 기본 통과 + PlatformDropThrough Raycast 착지
                 c.gameObject.layer = 8;
                 applied++;
                 if (appliedNames.Count < 8) appliedNames.Add($"{c.gameObject.name}({c.GetType().Name})");
             }
-            Debug.Log($"[BT27-JumpThrough] applied={applied} excluded={excluded} total={allColliders.Length}");
-            Debug.Log($"[BT27-JumpThrough] appliedSamples=[{string.Join(", ", appliedNames)}]");
+            Debug.Log($"[BT28-JumpThrough] applied={applied} excluded={excluded} total={allColliders.Length}");
+            Debug.Log($"[BT28-JumpThrough] appliedSamples=[{string.Join(", ", appliedNames)}]");
         }
     }
 }
diff --git a/Assets/Scripts/Mechanics/PlatformDropThrough.cs.meta b/Assets/Scripts/Mechanics/PlatformDropThrough.cs.meta
new file mode 100644
index 0000000..8725e6b
--- /dev/null
+++ b/Assets/Scripts/Mechanics/PlatformDropThrough.cs.meta
@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: bc0df74503a03ee478bb504a5cd1b0c3
\ No newline at end of file