diff --git a/index.html b/index.html
index 29b4d90..ad30756 100644
--- a/index.html
+++ b/index.html
@@ -15,6 +15,7 @@
           <p class="visual-warning">⚠️ Red squares are deadly - avoid them!</p>
           <p class="audio-warning">🔊 Hidden dangers end the game - listen for directions!</p>
           <p class="audio-hint">🗣️ Speech directions: "left", "right", "up", "down"</p>
+          <p class="probe-hint">👁️ Hold Shift + direction to detect invisible dangers!</p>
         </div>
         <canvas id="gameCanvas" width="800" height="600"></canvas>
         <div class="controls">
diff --git a/src/game.js b/src/game.js
index 232da01..f54bf86 100644
--- a/src/game.js
+++ b/src/game.js
@@ -137,6 +137,10 @@ export class Game {
     this.inputHandler.onMove = (direction) => {
       this.movePlayer(direction);
     };
+    
+    this.inputHandler.onProbe = (direction) => {
+      this.probeDirection(direction);
+    };
   }
   
   movePlayer(direction) {
@@ -160,6 +164,11 @@ export class Game {
         this.handleAudioDanger();
       }
       
+      // Check if player stepped on a hidden danger square
+      if (this.maze.isDangerousHidden(newX, newY)) {
+        this.handleHiddenDanger();
+      }
+      
       // Check if player reached the exit
       if (this.maze.isExit(newX, newY)) {
         this.handleWin();
@@ -167,6 +176,21 @@ export class Game {
     }
   }
   
+  probeDirection(direction) {
+    const probeX = this.player.x + direction.x;
+    const probeY = this.player.y + direction.y;
+    
+    // Check if probe position is within bounds
+    if (probeX < 0 || probeX >= this.maze.cols || probeY < 0 || probeY >= this.maze.rows) {
+      return;
+    }
+    
+    // Check if the probed square has a hidden danger
+    if (this.maze.isDangerousHidden(probeX, probeY)) {
+      this.handleHiddenDangerDetected();
+    }
+  }
+  
   trackMove(x, y) {
     // Track player move with timestamp
     const timestamp = Date.now();
@@ -188,6 +212,25 @@ export class Game {
     this.gameOver();
   }
   
+  handleHiddenDanger() {
+    // Hidden danger squares end the game
+    this.gameOver();
+  }
+  
+  handleHiddenDangerDetected() {
+    // Player detected a hidden danger with Shift+direction
+    console.log('Hidden danger detected!');
+    
+    // Try vibration first
+    if (this.vibrationEnabled && navigator.vibrate) {
+      navigator.vibrate([200, 100, 200]); // Danger detection pattern
+    } else {
+      // Fallback to caps lock toggle
+      this.inputHandler.toggleCapsLock();
+      console.log('Caps Lock toggled as vibration fallback');
+    }
+  }
+  
   gameOver() {
     if (this.soundEnabled) {
       this.audioSystem.playGameOverSound();
diff --git a/src/input.js b/src/input.js
index 9351b02..a39b8a5 100644
--- a/src/input.js
+++ b/src/input.js
@@ -2,6 +2,7 @@ export class InputHandler {
   constructor() {
     this.keys = new Set();
     this.onMove = null; // Callback for movement
+    this.onProbe = null; // Callback for probing with Shift+direction
     this.moveDelay = 150; // Milliseconds between moves
     this.lastMoveTime = 0;
     
@@ -36,6 +37,7 @@ export class InputHandler {
     }
     
     let direction = null;
+    const isShiftHeld = this.keys.has('ShiftLeft') || this.keys.has('ShiftRight');
     
     // Check for movement keys (WASD or Arrow keys)
     if (this.keys.has('KeyW') || this.keys.has('ArrowUp')) {
@@ -48,9 +50,16 @@ export class InputHandler {
       direction = { x: 1, y: 0 };
     }
     
-    if (direction && this.onMove) {
-      this.onMove(direction);
-      this.lastMoveTime = now;
+    if (direction) {
+      if (isShiftHeld && this.onProbe) {
+        // Shift is held, this is a probe action
+        this.onProbe(direction);
+        this.lastMoveTime = now;
+      } else if (!isShiftHeld && this.onMove) {
+        // Normal movement
+        this.onMove(direction);
+        this.lastMoveTime = now;
+      }
     }
   }
   
@@ -68,9 +77,33 @@ export class InputHandler {
       down: this.keys.has('KeyS') || this.keys.has('ArrowDown'),
       left: this.keys.has('KeyA') || this.keys.has('ArrowLeft'),
       right: this.keys.has('KeyD') || this.keys.has('ArrowRight'),
+      shift: this.keys.has('ShiftLeft') || this.keys.has('ShiftRight'),
     };
   }
   
+  // Toggle Caps Lock as fallback for vibration
+  toggleCapsLock() {
+    // Create a temporary input to simulate caps lock toggle
+    const temp = document.createElement('input');
+    temp.style.position = 'absolute';
+    temp.style.left = '-9999px';
+    document.body.appendChild(temp);
+    temp.focus();
+    
+    // Simulate caps lock key press
+    const event = new KeyboardEvent('keydown', {
+      key: 'CapsLock',
+      code: 'CapsLock',
+      keyCode: 20,
+      which: 20
+    });
+    temp.dispatchEvent(event);
+    
+    setTimeout(() => {
+      document.body.removeChild(temp);
+    }, 100);
+  }
+  
   // Clean up event listeners
   destroy() {
     document.removeEventListener('keydown', this.handleKeyDown);
diff --git a/src/maze.js b/src/maze.js
index f19ec2b..0e7f8cf 100644
--- a/src/maze.js
+++ b/src/maze.js
@@ -12,7 +12,8 @@ export class Maze {
     this.SAFE = 1;
     this.DANGEROUS_VISUAL = 2;  // Visually dangerous, no audio
     this.DANGEROUS_AUDIO = 3;   // Looks safe, has audio when near
-    this.EXIT = 4;
+    this.DANGEROUS_HIDDEN = 4;  // Invisible, only detectable with Shift+direction
+    this.EXIT = 5;
   }
   
   generate() {
@@ -89,16 +90,18 @@ export class Maze {
       }
     }
     
-    // Calculate target number of dangerous squares (30% of inner safe squares)
-    const totalDangerousCount = Math.floor(innerSafeSquares.length * 0.3);
-    const visualDangerousCount = Math.floor(totalDangerousCount * 0.5);
-    const audioDangerousCount = totalDangerousCount - visualDangerousCount;
+    // Calculate target number of dangerous squares (40% of inner safe squares)
+    const totalDangerousCount = Math.floor(innerSafeSquares.length * 0.4);
+    const visualDangerousCount = Math.floor(totalDangerousCount * 0.33);
+    const audioDangerousCount = Math.floor(totalDangerousCount * 0.33);
+    const hiddenDangerousCount = totalDangerousCount - visualDangerousCount - audioDangerousCount;
     
     this.shuffle(innerSafeSquares);
     
     let addedDangerous = 0;
     let addedVisual = 0;
     let addedAudio = 0;
+    let addedHidden = 0;
     
     // Add dangerous squares one by one, checking path after each addition
     for (let i = 0; i < innerSafeSquares.length && addedDangerous < totalDangerousCount; i++) {
@@ -110,6 +113,8 @@ export class Maze {
         dangerType = this.DANGEROUS_VISUAL;
       } else if (addedAudio < audioDangerousCount) {
         dangerType = this.DANGEROUS_AUDIO;
+      } else if (addedHidden < hiddenDangerousCount) {
+        dangerType = this.DANGEROUS_HIDDEN;
       } else {
         break; // We've added enough dangerous squares
       }
@@ -125,8 +130,10 @@ export class Maze {
         addedDangerous++;
         if (dangerType === this.DANGEROUS_VISUAL) {
           addedVisual++;
-        } else {
+        } else if (dangerType === this.DANGEROUS_AUDIO) {
           addedAudio++;
+        } else {
+          addedHidden++;
         }
       } else {
         // Path blocked, revert this square to safe
@@ -220,6 +227,10 @@ export class Maze {
     return this.grid[y][x] === this.DANGEROUS_AUDIO;
   }
   
+  isDangerousHidden(x, y) {
+    return this.grid[y][x] === this.DANGEROUS_HIDDEN;
+  }
+  
   isNearAudioDanger(playerX, playerY, range = 1) {
     // Check if player is within range of any audio danger squares
     for (let dy = -range; dy <= range; dy++) {
@@ -335,6 +346,41 @@ export class Maze {
             }
             break;
             
+          case this.DANGEROUS_HIDDEN:
+            if (debugMode) {
+              // In debug mode, show hidden danger squares with a purple overlay
+              ctx.fillStyle = '#ffffff';
+              ctx.fillRect(pixelX, pixelY, cellSize, cellSize);
+              
+              // Add purple debug overlay with pulsing effect
+              const hiddenTime = Date.now() * 0.004;
+              const hiddenPulse = (Math.sin(hiddenTime + x + y) + 1) * 0.5;
+              const hiddenAlpha = 0.3 + hiddenPulse * 0.4;
+              ctx.fillStyle = `rgba(128, 0, 128, ${hiddenAlpha})`;
+              ctx.fillRect(pixelX, pixelY, cellSize, cellSize);
+              
+              // Add debug border
+              ctx.strokeStyle = '#800080';
+              ctx.lineWidth = 2;
+              ctx.strokeRect(pixelX, pixelY, cellSize, cellSize);
+              
+              // Add hidden symbol
+              ctx.fillStyle = '#ffffff';
+              ctx.font = `${cellSize * 0.4}px Arial`;
+              ctx.textAlign = 'center';
+              ctx.textBaseline = 'middle';
+              ctx.fillText('👁️', pixelX + cellSize / 2, pixelY + cellSize / 2);
+            } else {
+              // In normal mode, hidden danger squares look identical to safe squares
+              ctx.fillStyle = '#ffffff';
+              ctx.fillRect(pixelX, pixelY, cellSize, cellSize);
+              // Add subtle grid lines
+              ctx.strokeStyle = '#e0e0e0';
+              ctx.lineWidth = 1;
+              ctx.strokeRect(pixelX, pixelY, cellSize, cellSize);
+            }
+            break;
+            
           case this.DANGEROUS_VISUAL:
             // Visual-only danger squares - animated red appearance
             const time = Date.now() * 0.003;
diff --git a/src/style.css b/src/style.css
index 4ee8228..2096ad3 100644
--- a/src/style.css
+++ b/src/style.css
@@ -80,6 +80,14 @@ h1 {
   opacity: 0.8;
 }
 
+.probe-hint {
+  color: #dda0dd !important;
+  font-size: 0.9em;
+  font-style: italic;
+  opacity: 0.8;
+  font-weight: bold;
+}
+
 @keyframes pulse {
   0%, 100% { opacity: 0.7; }
   50% { opacity: 1; }