diff --git a/src/components/WordBuilder.js b/src/components/WordBuilder.js
index a3e7e1f..ed0d73c 100644
--- a/src/components/WordBuilder.js
+++ b/src/components/WordBuilder.js
@@ -13,6 +13,8 @@ export function createWordBuilder({ onTileRemoved, onTilesReordered, onSubmitWor
     const hasTiles = tileCount > 0;
     const tileObjects = state.activeTileIds.map(id => state.boardTiles.find(t => t.id === id)).filter(Boolean);
     const pts = tileCount === 4 ? 8 : tileCount === 3 ? 4 : tileCount === 2 ? 2 : 1;
+    const constructedWord = tileObjects.map(t => t.text.toLowerCase()).join('');
+    const isAlreadyFound = hasTiles && state.foundWords.has(constructedWord);
 
     wrapper.innerHTML = `
       <div class="word-builder ${hasTiles ? 'has-tiles' : ''}" id="active-word-builder">
@@ -35,10 +37,10 @@ export function createWordBuilder({ onTileRemoved, onTilesReordered, onSubmitWor
           <button class="btn-icon-tray" id="btn-builder-backspace" title="Remove last tile" ${!hasTiles ? 'style="opacity:0.25;pointer-events:none;"' : ''}>
             ⌫
           </button>
-          <button class="btn-submit-tray" id="btn-builder-submit" ${!hasTiles ? 'disabled' : ''} title="Submit word (Enter)">
+          <button class="btn-submit-tray ${isAlreadyFound ? 'is-duplicate' : ''}" id="btn-builder-submit" ${!hasTiles ? 'disabled' : ''} title="${isAlreadyFound ? 'Word already found' : 'Submit word (Enter)'}">
             <span class="submit-icon">✓</span>
-            <span class="submit-text">ENTER</span>
-            ${hasTiles ? `<span class="submit-pts">+${pts}</span>` : ''}
+            <span class="submit-text">${isAlreadyFound ? 'FOUND' : 'ENTER'}</span>
+            ${hasTiles ? `<span class="submit-pts ${isAlreadyFound ? 'already-found' : ''}">${isAlreadyFound ? 'Found' : `+${pts}`}</span>` : ''}
           </button>
         </div>
       </div>
diff --git a/src/main.js b/src/main.js
index 2d4a2db..c71cd8f 100644
--- a/src/main.js
+++ b/src/main.js
@@ -174,8 +174,14 @@ async function initApp() {
     const result = gameState.submitWord();
 
     if (!result.success) {
-      sound.playError();
-      wordBuilder.triggerShake();
+      if (result.reason !== 'empty') {
+        sound.playError();
+        wordBuilder.triggerShake();
+        // Automatically erase selected tiles after shake so player doesn't have to keep hitting backspace/x
+        setTimeout(() => {
+          gameState.clearActive();
+        }, 400);
+      }
       return;
     }
 
diff --git a/src/state/game-state.js b/src/state/game-state.js
index c17a6f6..3265a3b 100644
--- a/src/state/game-state.js
+++ b/src/state/game-state.js
@@ -337,9 +337,7 @@ class GameStateManager {
     // Check if already found
     if (this.foundWords.has(constructedWord)) {
       this.notifyToast(`"${constructedWord.toUpperCase()}" already found!`, 'warning');
-      this.activeTileIds = [];
-      this.notify();
-      return { success: false, reason: 'duplicate' };
+      return { success: false, reason: 'duplicate', word: constructedWord };
     }
 
     // Look up in current puzzle's valid words list
@@ -347,7 +345,7 @@ class GameStateManager {
 
     if (!match) {
       this.notifyToast(`"${constructedWord.toUpperCase()}" is not in the word list`, 'error');
-      return { success: false, reason: 'invalid' };
+      return { success: false, reason: 'invalid', word: constructedWord };
     }
 
     // Valid word!
diff --git a/src/styles/board.css b/src/styles/board.css
index e2fc5b8..aef0559 100644
--- a/src/styles/board.css
+++ b/src/styles/board.css
@@ -186,6 +186,17 @@
   margin-left: 2px;
 }
 
+.btn-submit-tray.is-duplicate {
+  background: linear-gradient(135deg, #f59e0b, #d97706);
+  box-shadow: 0 2px 8px rgba(245, 158, 11, 0.35);
+}
+
+.submit-pts.already-found {
+  background: rgba(0, 0, 0, 0.22);
+  color: #ffffff;
+  font-weight: 800;
+}
+
 @media (max-width: 420px) {
   .word-builder {
     padding: 3px 6px;