@@ -142,8 +142,9 @@
 		case Keys.UP:    fn('U'); break;
 		case Keys.LEFT:  fn('L'); break;
 		case Keys.RIGHT: fn('R'); break;
 		case Keys.W:     fn('W'); break;
+		case Keys.S:     fn('S'); break;
 		case Keys.A:     fn('A'); break;
 		case Keys.G:     fn(solver.single_step()); break;
 		default:         break;
 		}