diff --git a/apps.json b/apps.json
index 7aeae8749..4a3d8c7c8 100644
--- a/apps.json
+++ b/apps.json
@@ -5393,7 +5393,7 @@
   {
     "id": "puzzle15",
     "name": "15 puzzle",
-    "version": "0.01",
+    "version": "0.02",
     "description": "A 15 puzzle game with drag gesture interface",
     "readme":"README.md",
     "icon": "puzzle15.app.png",
diff --git a/apps/puzzle15/ChangeLog b/apps/puzzle15/ChangeLog
index 2f5d93cad..bc5a4422b 100644
--- a/apps/puzzle15/ChangeLog
+++ b/apps/puzzle15/ChangeLog
@@ -1 +1,2 @@
 0.01: Initial version, UI mechanics ready, no real game play so far
+0.02: Lots of enhancements, menu system not yet functional, but packaging should be now...
diff --git a/apps/puzzle15/puzzle15.app.js b/apps/puzzle15/puzzle15.app.js
index 9a5864b9a..801cdf759 100644
--- a/apps/puzzle15/puzzle15.app.js
+++ b/apps/puzzle15/puzzle15.app.js
@@ -8,14 +8,14 @@
 // Minimum number of pixels to interpret it as drag gesture
 const dragThreshold = 10;
 
+// Maximum number of pixels to interpret a click from a drag event series
+const clickThreshold = 3;
+
 // Number of steps in button move animation
-const animationSteps = 5;
+const animationSteps = 6;
 
 // Milliseconds to wait between move animation steps
-const animationWaitMillis = 70;
-
-// Size of the playing field
-const buttonsPerLine = 4;
+const animationWaitMillis = 30;
 
 // *** Global settings derived by device characteristics
 
@@ -25,14 +25,29 @@ const fieldw = g.getWidth();
 // Total height of the playing field (screen height minus widget zones)
 const fieldh = g.getHeight() - 48;
 
+// Size of the playing field
+var buttonsPerLine;
+
 // Size of one button
-const buttonsize = Math.floor(Math.min(fieldw / (buttonsPerLine + 1), fieldh / buttonsPerLine)) - 2;
+var buttonsize;
 
 // Actual left start of the playing field (so that it is centered)
-const leftstart = (fieldw - ((buttonsPerLine + 1) * buttonsize + 8)) / 2;
+var leftstart;
 
 // Actual top start of the playing field (so that it is centered)
-const topstart = 24 + ((fieldh - (buttonsPerLine * buttonsize + 6)) / 2);
+var topstart;
+
+// Number of buttons on the board (needed at several occasions)
+var buttonsPerBoard;
+
+// Set the buttons per line globally and all derived values, too
+function setButtonsPerLine(bPL) {
+  buttonsPerLine = bPL;
+  buttonsize = Math.floor(Math.min(fieldw / (buttonsPerLine + 1), fieldh / buttonsPerLine)) - 2;
+  leftstart = (fieldw - ((buttonsPerLine + 1) * buttonsize + 8)) / 2;
+  topstart = 24 + ((fieldh - (buttonsPerLine * buttonsize + 6)) / 2);
+  buttonsPerBoard = (buttonsPerLine * buttonsPerLine);
+}
 
 // *** Low level helper classes
 
@@ -67,7 +82,7 @@ class Fifo {
   remove() {
     if (this.first === null)
       return null;
-    oldfirst = this.first;
+    let oldfirst = this.first;
     this.first = this.first.next;
     if (this.first === null)
       this.last = null;
@@ -110,6 +125,56 @@ class Worker {
   }
 }
 
+// Evaluate "drag" events from the UI and call handlers for drags or clicks
+// The UI sends a drag as a series of events indicating partial movements
+// of the finger.
+// This class combines such parts to a long drag from start to end
+// If the drag is short, it is interpreted as click,
+// otherwise as drag.
+// The approprate method is called with the data of the drag.
+class Dragger {
+  constructor(clickHandler, dragHandler, clickThreshold, dragThreshold) {
+    this.clickHandler = clickHandler;
+    this.dragHandler = dragHandler;
+    this.clickThreshold = (clickThreshold === undefined ? 3 : clickThreshold);
+    this.dragThreshold = (dragThreshold === undefined ? 10 : dragThreshold);
+    this.dx = 0;
+    this.dy = 0;
+    this.enabled = true;
+  }
+  // Enable or disable the Dragger
+  setEnabled(b) {
+    this.enabled = b;
+  }
+  // Handle a raw drag event from the UI
+  handleRawDrag(e) {
+    if (!this.enabled)
+      return;
+    this.dx += e.dx; // Always accumulate
+    this.dy += e.dy;
+    if (e.b === 0) { // Drag event ended: Evaluate full drag
+      if (Math.abs(this.dx) < this.clickThreshold && Math.abs(this.dy) < this.clickThreshold)
+        this.clickHandler({
+          x: e.x - this.dx,
+          y: e.y - this.dy
+        }); // take x and y from the drag start
+      else if (Math.abs(this.dx) > this.dragThreshold || Math.abs(this.dy) > this.dragThreshold)
+        this.dragHandler({
+          x: e.x - this.dx,
+          y: e.y - this.dy,
+          dx: this.dx,
+          dy: this.dy
+        });
+      this.dx = 0; // Clear the drag accumulator
+      this.dy = 0;
+    }
+  }
+  // Attach the drag evaluator to the UI
+  attach() {
+    Bangle.on("drag", e => this.handleRawDrag(e));
+  }
+}
+
 // *** Mid-level game mechanics
 
 // Representation of a position where a stone is set.
@@ -127,6 +192,11 @@ class Field {
     this.centerx = (left + buttonsize / 2) + 1;
     this.centery = (top + buttonsize / 2) + 2;
   }
+  // Returns whether this field contains the given coordinate
+  contains(x, y) {
+    return (this.left < x && this.left + buttonsize > x &&
+      this.top < y && this.top + buttonsize > y);
+  }
   // Generate a field for the given playing field index.
   // Playing field indexes start at top left with "0"
   // and go from left to right line by line from top to bottom.
@@ -134,6 +204,16 @@ class Field {
     return new Field(leftstart + (index % buttonsPerLine) * (buttonsize + 2),
       topstart + (Math.floor(index / buttonsPerLine)) * (buttonsize + 2));
   }
+  // Special field for the result "stone"
+  static forResult() {
+    return new Field(leftstart + (buttonsPerLine * (buttonsize + 2)),
+      topstart + ((buttonsPerLine - 1) * (buttonsize + 2)));
+  }
+  // Special field for the menu
+  static forMenu() {
+    return new Field(leftstart + (buttonsPerLine * (buttonsize + 2)),
+      topstart);
+  }
 }
 
 // Representation of a moveable stone of the game.
@@ -217,11 +297,11 @@ class Mover extends Clearer {
   animateStep(step, worker) {
     this.clearArea();
     this.stone.draw(this.stepField(step));
-    if (step < this.steps)  // still steps left: Issue next step
+    if (step < this.steps) // still steps left: Issue next step
       setTimeout(function(t) {
         t.animateStep(step + 1, worker);
       }, animationWaitMillis, this);
-    else  // all steps done: Inform the worker
+    else // all steps done: Inform the worker
       worker.endTask();
   }
   // Start the animation, this method is called by the worker
@@ -232,22 +312,54 @@ class Mover extends Clearer {
 
 // Representation of the playing field
 // Knows to draw the field and to move a stone into a gap
-// TODO: More game mechanics (shuffling, solving,...)
+// TODO: More game mechanics (solving,...)
 class Board {
   // Generates the actual playing field with all fields and buttons
   constructor() {
     this.fields = [];
-    this.buttons = [];
-    for (i = 0; i < (buttonsPerLine * buttonsPerLine); i++) {
+    this.resultField = Field.forResult();
+    this.menuField = Field.forMenu();
+    for (i = 0; i < buttonsPerBoard; i++)
       this.fields[i] = Field.forIndex(i);
-      this.buttons[i] = new Stone((i + 1) % (buttonsPerLine * buttonsPerLine),i);
+    this.setShuffled();
+  }
+  // Set the board into the "solved" position
+  setSolved() {
+    this.buttons = [];
+    for (i = 0; i < buttonsPerBoard; i++)
+      this.buttons[i] = new Stone((i + 1) % buttonsPerBoard, i);
+    this.moveCount = 0;
+  }
+  setShuffled() {
+    let nrs = [];
+    for (i = 0; i < buttonsPerBoard; i++)
+      nrs[i] = i;
+    this.buttons = [];
+    let count = buttonsPerBoard;
+    for (i = 0; i < buttonsPerBoard; i++) {
+      let curridx = Math.floor(Math.random() * count);
+      let currnr = nrs[curridx];
+      this.buttons[i] = new Stone(currnr, (currnr + (buttonsPerBoard - 1)) % buttonsPerBoard);
+      for (j = curridx + 1; j < count; j++)
+        nrs[j - 1] = nrs[j];
+      count -= 1;
     }
+    if (!this.isSolvable()) {
+      let a = (this.buttons[0].number === 0 ? 2 : 0);
+      let b = (this.buttons[1].number === 0 ? 2 : 1);
+      let bx = this.buttons[a];
+      this.buttons[a] = this.buttons[b];
+      this.buttons[b] = bx;
+    }
+    this.moveCount = 0;
   }
   // Draws the complete playing field
   draw() {
     new Clearer(this.fields[0], this.fields[this.fields.length - 1]).clearArea();
     for (i = 0; i < this.fields.length; i++)
       this.buttons[i].draw(this.fields[i]);
+    this.drawResult(null);
+    this.drawMenu();
   }
   // returns the index of the field left of the field with the given index,
   // -1 if there is none (index indicates already a leftmost field on the board)
@@ -270,36 +382,44 @@ class Board {
         return i;
     return -1;
   }
+  // Returns the row in which the gap is, 0 is upmost
+  rowOf0() {
+    let idx = this.indexOf0();
+    if (idx < 0)
+      return -1;
+    return Math.floor(idx / buttonsPerLine);
+  }
   // Moves the stone at the field with the index found by the startfunc operation
   // into the gap field.
-  moveTo0(startfunc, animator) {
+  moveTo0(startfunc, worker) {
     let endidx = this.indexOf0(); // Target field (the gap)
     if (endidx === -1) {
-      animator.endTask();
+      worker.endTask();
       return;
     }
-    let startidx = startfunc(endidx);  // Start field (relative to the gap)
+    let startidx = startfunc(endidx); // Start field (relative to the gap)
     if (startidx === -1) {
-      animator.endTask();
+      worker.endTask();
       return;
     }
     let moved = this.buttons[startidx];
     this.buttons[startidx] = this.buttons[endidx];
     this.buttons[endidx] = moved;
-    new Mover(moved, this.fields[startidx], this.fields[endidx], animationSteps).animate(animator);
+    this.moveCount += 1;
+    new Mover(moved, this.fields[startidx], this.fields[endidx], animationSteps).animate(worker);
   }
   // Move the stone right fro the gap into the gap
-  moveRight(animator) {
-    this.moveTo0(this.leftOf, animator);
+  moveRight(worker) {
+    this.moveTo0(this.leftOf, worker);
   }
-  moveLeft(animator) {
-    this.moveTo0(this.rightOf, animator);
+  moveLeft(worker) {
+    this.moveTo0(this.rightOf, worker);
   }
-  moveUp(animator) {
-    this.moveTo0(this.bottomOf, animator);
+  moveUp(worker) {
+    this.moveTo0(this.bottomOf, worker);
   }
-  moveDown(animator) {
-    this.moveTo0(this.topOf, animator);
+  moveDown(worker) {
+    this.moveTo0(this.topOf, worker);
   }
   // Check if the board is solved (all stones at the right position)
   isSolved() {
@@ -308,54 +428,152 @@ class Board {
         return false;
     return true;
   }
+  // counts the inversions on the board
+  // see https://www.geeksforgeeks.org/check-instance-15-puzzle-solvable/
+  getInversionCount() {
+    let inversions = 0;
+    for (outer = 0; outer < buttonsPerBoard - 1; outer++) {
+      let outernr = this.buttons[outer].number;
+      if (outernr === 0)
+        continue;
+      for (inner = outer + 1; inner < buttonsPerBoard; inner++) {
+        let innernr = this.buttons[inner].number;
+        if (innernr > 0 && outernr > innernr)
+          inversions++;
+      }
+    }
+    return inversions;
+  }
+  // return whether the puzzle is solvable
+  // see https://www.geeksforgeeks.org/check-instance-15-puzzle-solvable/
+  isSolvable() {
+    let invs = this.getInversionCount();
+    if (buttonsPerLine % 2 !== 0) // odd number of rows/columns
+      return (invs % 2 === 0);
+    else {
+      return ((invs + this.rowOf0()) % 2 !== 0);
+    }
+  }
+  // draw the result field, pass null as argument if not called from worker
+  drawResult(worker) {
+    let field = this.resultField;
+    if (this.isSolved())
+      g.setColor(0, 1, 0);
+    else
+      g.setColor(1, 0, 0);
+    g.fillRect(field.left, field.top, field.left + buttonsize, field.top + buttonsize);
+    g.setColor(0, 0, 0);
+    g.drawRect(field.left, field.top, field.left + buttonsize, field.top + buttonsize);
+    g.setFont("Vector", 14).setFontAlign(0, 0).drawString(this.moveCount, field.centerx, field.centery);
+    if (worker !== null)
+      worker.endTask();
+  }
+  // draws the menu button
+  drawMenu() {
+    let field = this.menuField;
+    g.setColor(0.5, 0.5, 0.5);
+    g.fillRect(field.left, field.top, field.left + buttonsize, field.top + buttonsize);
+    g.setColor(0, 0, 0);
+    g.drawRect(field.left, field.top, field.left + buttonsize, field.top + buttonsize);
+    let l = field.left + 8;
+    let r = field.left + buttonsize - 8;
+    let t = field.top + 5;
+    for (i = 0; i < 3; i++)
+      g.fillRect(l, t + (i * 7), r, t + (i * 7) + 3);
+  }
 }
 
+/*
+// Main class, containing the complete game logic
+class Puzzle15 {
+  constructor() {
+    this.worker=new Worker();
+    this.board=new Board();
+  }
+}
+*/
+
 // *** Main program
 
 // We need a worker...
 var worker = new Worker();
+
+setButtonsPerLine(3);
 // ...and the board
 var board = new Board();
 
-// UI: Accumulation of current drag operation
-var currentdrag = {
-  x: 0,
-  y: 0
-};
+var dragger;
+
+function initGame(bpl) {
+  setButtonsPerLine(bpl);
+  board = new Board();
+  board.draw();
+  dragger.setEnabled(true);
+}
+
+function showMenu() {
+  var mainmenu = {
+    "": {
+      "title": "15 Puzzle"
+    },
+    "< Back": () => {
+      E.showMenu();
+      dragger.setEnabled(true);
+      board.draw();
+    }, // remove the menu
+    "Start 3x3": function() {
+      E.showMenu();
+      initGame(3);
+    },
+    "Start 4x4": function() {
+      E.showMenu();
+      initGame(4);
+    },
+    "Start 5x5": function() {
+      E.showMenu();
+      initGame(5);
+    }
+  };
+  dragger.setEnabled(false);
+
+  E.showMenu(mainmenu);
+}
+
+function handleclick(e) {
+  if (board.menuField.contains(e.x, e.y)) {
+    console.log("GGG - handleclick, dragger: " + dragger);
+    g.reset();
+    showMenu();
+    console.log("showing menu ended");
+  }
+}
 
 // Handle a drag event
 function handledrag(e) {
-  if (e.b === 0) { // Drag event ended: Evaluate drag and start move operation
-    if (Math.abs(currentdrag.x) > Math.abs(currentdrag.y)) { // Horizontal drag
-      if (currentdrag.x > dragThreshold)
-        worker.addTask(e => board.moveRight(e));
-      else if (currentdrag.x < -dragThreshold)
-        worker.addTask(e => board.moveLeft(e));
-    } else { // Vertical drag
-      if (currentdrag.y > dragThreshold)
-        worker.addTask(e => board.moveDown(e));
-      else if (currentdrag.y < -dragThreshold)
-        worker.addTask(e => board.moveUp(e));
-    }
-    currentdrag.x = 0; // Clear the drag accumulator
-    currentdrag.y = 0;
-  } else { // Drag still running: Accumulate drag shifts
-    currentdrag.x += e.dx;
-    currentdrag.y += e.dy;
-  }
+  worker.addTask(Math.abs(e.dx) > Math.abs(e.dy) ?
+    (e.dx > 0 ? e => board.moveRight(e) : e => board.moveLeft(e)) :
+    (e.dy > 0 ? e => board.moveDown(e) : e => board.moveUp(e)));
+  worker.addTask(e => board.drawResult(e));
 }
 
 // Clear the screen once, at startup
 g.clear();
-// Drop mode as this is a game
-Bangle.setUI(undefined);
+
+// Clock mode allows short-press on button to exit
+Bangle.setUI("clock");
 // Load widgets
 Bangle.loadWidgets();
 Bangle.drawWidgets();
 
 // Draw the board initially
 board.draw();
+
+dragger = new Dragger(handleclick, handledrag, clickThreshold, dragThreshold);
+
+showMenu();
 // Start the interaction
-Bangle.on("drag", handledrag);
+dragger.attach();
+
+console.log("GGG - main program, dragger: " + dragger);
 
 // end of file
\ No newline at end of file