diff -r f1bbe12e2c3d -r 16b711a81a16 2048.html
--- a/2048.html	Tue Sep 09 20:33:17 2014 +0300
+++ b/2048.html	Tue Sep 09 21:18:31 2014 +0300
@@ -37,6 +37,9 @@
     div.move-control, div.score-conrol {
       padding: 3px;
     }
+    div.move-control button.suggestion {
+      background-color: cyan;
+    }
     div.ai-control {
       padding: 2px 2px 2px 1em;
     }
@@ -301,6 +304,7 @@
     ui.action.start = function() {
       ui.score.clear();
       ui.message.clear();
+      ui.action.clearSuggestion();
       board.current = board.create();
       board.putRandom(board.current);
       ui.board.update(board.current);
@@ -308,6 +312,7 @@
     document.getElementById("start").addEventListener("click", ui.action.start);
 
     ui.action.up = function() {
+      ui.action.clearSuggestion();
       var updated = board.move.up(board.current);
       if (updated) {
         board.putRandom(board.current);
@@ -318,6 +323,7 @@
     }
     document.getElementById("up").addEventListener("click", ui.action.up);
     ui.action.down = function() {
+      ui.action.clearSuggestion();
       var updated = board.move.down(board.current);
       if (updated) {
         board.putRandom(board.current);
@@ -328,6 +334,7 @@
     }
     document.getElementById("down").addEventListener("click", ui.action.down);
     ui.action.left = function() {
+      ui.action.clearSuggestion();
       var updated = board.move.left(board.current);
       if (updated) {
         board.putRandom(board.current);
@@ -338,6 +345,7 @@
     }
     document.getElementById("left").addEventListener("click", ui.action.left);
     ui.action.right = function() {
+      ui.action.clearSuggestion();
       var updated = board.move.right(board.current);
       if (updated) {
         board.putRandom(board.current);
@@ -372,32 +380,68 @@
       messageDom.innerHTML = msg;
     }
 
-    function step() {
-      ui.message.clear();
+    ui.action.checkGameOver = function() {
       if (board.gameOver(board.current)) {
         ui.message.set("Game over!");
+        return true;
+      } else {
+        return false;
+      }
+    }
+    ui.action.checkMoveValid = function(move) {
+      var tmpBrd = board.create();
+      board.copy(board.current, tmpBrd);
+      if (!(move in {"left":0,"right":0,"up":0,"down":0})) {
+        ui.message.set("AI can't find move!");
+        return false;
+      }
+      if ( ! board.move[move].call(null, tmpBrd)) {
+        ui.message.set("AI move "+move+" is ivalid!");
+        return false;
+      }
+      return true;
+    }
+
+    ui.action.clearSuggestion = function() {
+      var btns = document.querySelectorAll('div.move-control button');
+      for (var i = 0; i < btns.length; i++)
+        btns[i].classList.remove('suggestion');
+    }
+    ui.action.suggest = function() {
+      ui.action.clearSuggestion();
+      ui.message.clear();
+      if (ui.action.checkGameOver())
         return;
-      }
       var tmpBrd = board.create();
       board.copy(board.current, tmpBrd);
       var move = ui.ai.current.analyse(tmpBrd);
-      if (typeof move === 'undefined') {
-        ui.message.set("I don't know how to move!");
+      ui.ai.current.cleanup();
+      if ( ! ui.action.checkMoveValid(move))
+        return;
+      document.getElementById(move).classList.add('suggestion');
+    }
+    document.getElementById("suggest").addEventListener("click", ui.action.suggest);
+    ui.action.step = function() {
+      ui.message.clear();
+      ui.action.clearSuggestion();
+      if (ui.action.checkGameOver())
         return;
-      }
-      var updated = board.move[move].call(null, board.current);
-      if (updated) {
-        board.putRandom(board.current);
-        ui.board.update(board.current);
-        ui.score.update(board.current);
-      } else {
-        ui.message.set("Wrong move!");
-      }
+      var tmpBrd = board.create();
+      board.copy(board.current, tmpBrd);
+      var move = ui.ai.current.analyse(tmpBrd);
+      ui.ai.current.cleanup();
+      if ( ! ui.action.checkMoveValid(move))
+        return;
+      board.move[move].call(null, board.current);
+      board.putRandom(board.current);
+      ui.board.update(board.current);
+      ui.score.update(board.current);
     }
-    document.getElementById("step").addEventListener("click", step);
+    document.getElementById("step").addEventListener("click", ui.action.step);
 
     ui.action.finish = function() {
       ui.message.clear();
+      ui.action.clearSuggestion();
       var step = 0;
       var tsFrom = new Date().getTime();
       while (!board.gameOver(board.current)) {