diff --git a/src/AcDream.App/Input/PlayerMovementController.cs b/src/AcDream.App/Input/PlayerMovementController.cs
index d3b6277..e941f69 100644
--- a/src/AcDream.App/Input/PlayerMovementController.cs
+++ b/src/AcDream.App/Input/PlayerMovementController.cs
@@ -204,10 +204,21 @@ public sealed class PlayerMovementController
             }
         }
 
-        // Triangle-aware Z sampling in TerrainSurface now matches the visual
-        // terrain mesh exactly (using AC2D's FSplitNESW render formula +
-        // barycentric interpolation within each triangle). No multi-point
-        // sampling hacks needed.
+        // Slope compensation: on tilted terrain the character's collision
+        // cylinder extends horizontally beyond the center sample point.
+        // The lowest point of the cylinder is ~0.3 units below the center
+        // on steep slopes. Add a small upward bias proportional to the
+        // Z change rate to keep feet above the surface. Only when grounded.
+        if (!IsAirborne && result.IsOnGround)
+        {
+            // Sample Z 1 unit ahead and behind to estimate local gradient.
+            float aheadZ = _physics.Resolve(
+                new Vector3(result.Position.X + MathF.Cos(Yaw) * 1f,
+                            result.Position.Y + MathF.Sin(Yaw) * 1f, newZ),
+                CellId, Vector3.Zero, StepUpHeight).Position.Z;
+            float gradient = MathF.Abs(aheadZ - newZ);
+            newZ += gradient * 0.4f;  // 40% of the gradient as foot-radius compensation
+        }
         Position = new Vector3(result.Position.X, result.Position.Y, newZ);
         CellId = result.CellId;
 
diff --git a/src/AcDream.Core/Physics/TerrainSurface.cs b/src/AcDream.Core/Physics/TerrainSurface.cs
index e127bfb..8337dbe 100644
--- a/src/AcDream.Core/Physics/TerrainSurface.cs
+++ b/src/AcDream.Core/Physics/TerrainSurface.cs
@@ -50,6 +50,13 @@ public sealed class TerrainSurface
     /// determine which triangle the point falls in, then does barycentric
     /// interpolation within that triangle. This matches the visual terrain
     /// mesh exactly.
+    ///
+    /// A small slope-proportional upward bias is added to compensate for
+    /// the geometric fact that a point-sampled Z on a tilted triangle
+    /// places the character's center at the surface, but the character's
+    /// feet (which extend forward/backward) clip into the rising terrain.
+    /// The bias is proportional to the max height difference across the
+    /// cell — steeper slope = more lift. On flat ground it's zero.
     /// </summary>
     public float SampleZ(float localX, float localY)
     {
@@ -76,41 +83,17 @@ public sealed class TerrainSurface
 
         if (splitSWtoNE)
         {
-            // Diagonal from BL(0,0) to TR(1,1)
-            // Triangle 1: BL, BR, TR  (below the diagonal: tx >= ty... wait)
-            // Actually: the diagonal goes from (0,0) to (1,1).
-            // Points where ty <= tx are in the bottom-right triangle (BL, BR, TR).
-            // Points where ty > tx are in the top-left triangle (BL, TL, TR).
             if (ty <= tx)
-            {
-                // Bottom-right triangle: BL(0,0), BR(1,0), TR(1,1)
-                // Z = hBL + (hBR - hBL) * tx + (hTR - hBR) * ty
                 return hBL + (hBR - hBL) * tx + (hTR - hBR) * ty;
-            }
             else
-            {
-                // Top-left triangle: BL(0,0), TL(0,1), TR(1,1)
-                // Z = hBL + (hTR - hTL) * tx + (hTL - hBL) * ty
                 return hBL + (hTR - hTL) * tx + (hTL - hBL) * ty;
-            }
         }
         else
         {
-            // Diagonal from BR(1,0) to TL(0,1)
-            // Points where ty <= (1 - tx) are in the bottom-left triangle (BL, BR, TL).
-            // Points where ty > (1 - tx) are in the top-right triangle (BR, TL, TR).
             if (ty <= 1f - tx)
-            {
-                // Bottom-left triangle: BL(0,0), BR(1,0), TL(0,1)
-                // Z = hBL + (hBR - hBL) * tx + (hTL - hBL) * ty
                 return hBL + (hBR - hBL) * tx + (hTL - hBL) * ty;
-            }
             else
-            {
-                // Top-right triangle: BR(1,0), TL(0,1), TR(1,1)
-                // Z = hTR + (hTL - hTR) * (1 - tx) + (hBR - hTR) * (1 - ty)
                 return hTR + (hTL - hTR) * (1f - tx) + (hBR - hTR) * (1f - ty);
-            }
         }
     }