diff --git a/README.md b/README.md
index 92cfd002..fd5681c8 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,7 @@ Bug Fixes:
 * Moved 'dirty' flag for Tilemap to a per-layer flag. Fixes #242
 * Group.length now returns the number of children in the Group regardless of their exists/alive state, or 0 if the Group is has no children.
 * Switch Camera.setBoundsToWorld to match world.bounds instead of world (thanks cocoademon)
+* Fixed an issue where passing null as the Group parent wouldn't set it to game.world as it should have (thanks tito100)
 
 
 You can view the Change Log for all previous versions at https://github.com/photonstorm/phaser/changelog.md
diff --git a/examples/wip/tilemap.js b/examples/wip/tilemap.js
index 7de691ee..09e8517f 100644
--- a/examples/wip/tilemap.js
+++ b/examples/wip/tilemap.js
@@ -36,8 +36,8 @@ function create() {
     //  this screws something up - not quite sure what, but needs investigating!
     // layer.resizeWorld();
 
-    sprite = game.add.sprite(120, 510, 'phaser');
-    sprite.anchor.setTo(0.5, 0.5);
+    sprite = game.add.sprite(120, 450, 'phaser');
+    // sprite.anchor.setTo(0.5, 0.5);
     // sprite.angle = 5;
 
     // game.camera.follow(sprite);
@@ -96,12 +96,12 @@ function update() {
     if (cursors.left.isDown)
     {
         sprite.body.velocity.x = -150;
-        sprite.scale.x = -1;
+        // sprite.scale.x = -1;
     }
     else if (cursors.right.isDown)
     {
         sprite.body.velocity.x = 150;
-        sprite.scale.x = 1;
+        // sprite.scale.x = 1;
     }
 
 
@@ -113,6 +113,6 @@ function render() {
     // game.debug.renderSpriteBounds(sprite);
 
     game.debug.renderText(sprite.x, 32, 32);
-    game.debug.renderText(sprite.y, 32, 64);
+    game.debug.renderText(sprite.y, 32, 48);
 
 }
\ No newline at end of file
diff --git a/src/core/Group.js b/src/core/Group.js
index fdf199e3..0fe18896 100644
--- a/src/core/Group.js
+++ b/src/core/Group.js
@@ -10,32 +10,32 @@
 * @classdesc A Group is a container for display objects that allows for fast pooling, recycling and collision checks.
 * @constructor
 * @param {Phaser.Game} game - A reference to the currently running game.
-* @param {*} parent - The parent Group or DisplayObjectContainer that will hold this group, if any.
+* @param {*} parent - The parent Group or DisplayObjectContainer that will hold this group, if any. If not set, or set to null, it will use game.world.
 * @param {string} [name=group] - A name for this Group. Not used internally but useful for debugging.
 * @param {boolean} [useStage=false] - Should the DisplayObjectContainer this Group creates be added to the World (default, false) or direct to the Stage (true).
 */
 Phaser.Group = function (game, parent, name, useStage) {
 
-    if (typeof parent === 'undefined' || typeof parent === null)
+    /**
+    * @property {Phaser.Game} game - A reference to the currently running Game.
+    */
+    this.game = game;
+
+    if (typeof parent === 'undefined' || parent === null)
     {
         parent = game.world;
     }
 
+    /**
+    * @property {string} name - A name for this Group. Not used internally but useful for debugging.
+    */
+    this.name = name || 'group';
+
     if (typeof useStage === 'undefined')
     {
         useStage = false;
     }
 
-    /**
-    * @property {Phaser.Game} game - A reference to the currently running Game.
-    */
-    this.game = game;
-    
-    /**
-    * @property {string} name - A name for this Group. Not used internally but useful for debugging.
-    */
-    this.name = name || 'group';
-
     if (useStage)
     {
         this._container = this.game.stage._stage;
diff --git a/src/gameobjects/GameObjectFactory.js b/src/gameobjects/GameObjectFactory.js
index 872b89ff..4996b334 100644
--- a/src/gameobjects/GameObjectFactory.js
+++ b/src/gameobjects/GameObjectFactory.js
@@ -90,7 +90,7 @@ Phaser.GameObjectFactory.prototype = {
     *
     * @method Phaser.GameObjectFactory#group
     * @param {*} parent - The parent Group or DisplayObjectContainer that will hold this group, if any.
-    * @param {string} [name=group] - A name for this Group. Not used internally but useful for debugging.
+    * @param {string} [name='group'] - A name for this Group. Not used internally but useful for debugging.
     * @return {Phaser.Group} The newly created group.
     */
     group: function (parent, name) {
diff --git a/src/geom/Rectangle.js b/src/geom/Rectangle.js
index c27aca20..db9c4c79 100644
--- a/src/geom/Rectangle.js
+++ b/src/geom/Rectangle.js
@@ -644,7 +644,14 @@ Phaser.Rectangle.intersection = function (a, b, out) {
 */
 Phaser.Rectangle.intersects = function (a, b) {
 
-    return (a.x < b.right && b.x < a.right && a.y < b.bottom && b.y < a.bottom);
+    if (a.width <= 0 || a.height <= 0 || b.width <= 0 || b.height <= 0)
+    {
+        return false;
+    }
+
+    return !(a.right < b.x || a.bottom < b.y || a.x > b.right || a.y > b.bottom);
+
+    // return (a.x < b.right && b.x < a.right && a.y < b.bottom && b.y < a.bottom);
 
     // return (a.x <= b.right && b.x <= a.right && a.y <= b.bottom && b.y <= a.bottom);
 
diff --git a/src/physics/arcade/ArcadePhysics.js b/src/physics/arcade/ArcadePhysics.js
index ad3b1057..ca382870 100644
--- a/src/physics/arcade/ArcadePhysics.js
+++ b/src/physics/arcade/ArcadePhysics.js
@@ -566,6 +566,8 @@ Phaser.Physics.Arcade.prototype = {
             return;
         }
 
+        console.log('collideSpriteVsTilemapLayer', this._mapData.length);
+
         for (var i = 0; i < this._mapData.length; i++)
         {
             if (this.separateTile(sprite.body, this._mapData[i]))
@@ -1006,20 +1008,27 @@ Phaser.Physics.Arcade.prototype = {
             return false;
         }
 
-        var overlapX = 0;
-        var overlapY = 0;
+        //  use body var instead
+        body.overlapX = 0;
+        body.overlapY = 0;
 
-        console.log('x', tile.x, 'y', tile.y, 'r', tile.right, 'b', tile.bottom);
-        console.log('x', body.x, 'y', body.y, 'r', body.right, 'b', body.bottom);
-        console.log(Phaser.Rectangle.intersects(body, tile));
+        //  Remember - this happens AFTER the body has been moved by the motion update, so it needs moving back again
+        // console.log('---------------------------------------------------------------------------------------------');
+        // console.log('tx', tile.x, 'ty', tile.y, 'tw', tile.width, 'th', tile.height, 'tr', tile.right, 'tb', tile.bottom);
+        // console.log('bx', body.x, 'by', body.y, 'bw', body.width, 'bh', body.height, 'br', body.right, 'bb', body.bottom);
+        // console.log(Phaser.Rectangle.intersects(body, tile));
+        // console.log('dx', body.deltaX(), 'dy', body.deltaY(), 'dax', body.deltaAbsX(), 'day', body.deltaAbsY(), 'cax', Math.ceil(body.deltaAbsX()), 'cay', Math.ceil(body.deltaAbsY()));
 
         if (body.deltaX() < 0 && body.allowCollision.left && tile.tile.faceRight)
         {
             //  LEFT
-            if (tile.right - body.x < Math.ceil(body.deltaAbsX()))
-            {
-                overlapX = tile.right - body.x;
+            body.overlapX = body.x - tile.right;
 
+            if (body.overlapX > body.deltaX())
+            {
+                console.log('left overlapX', body.overlapX);
+                //  use touching instead of blocked?
+                body.blocked.left = true;
                 body.touching.left = true;
                 body.touching.none = false;
             }
@@ -1027,10 +1036,13 @@ Phaser.Physics.Arcade.prototype = {
         else if (body.deltaX() > 0 && body.allowCollision.right && tile.tile.faceLeft)
         {
             //  RIGHT
-            if (body.right - tile.x < Math.ceil(body.deltaAbsX()))
-            {
-                overlapX = tile.x - body.right;
+            body.overlapX = body.right - tile.x;
 
+            //  Distance check
+            if (body.overlapX < body.deltaX())
+            {
+                console.log('right overlapX', body.overlapX);
+                body.blocked.right = true;
                 body.touching.right = true;
                 body.touching.none = false;
             }
@@ -1039,10 +1051,13 @@ Phaser.Physics.Arcade.prototype = {
         if (body.deltaY() < 0 && body.allowCollision.up && tile.tile.faceBottom)
         {
             //  UP
-            if (tile.bottom - body.y < Math.ceil(body.deltaAbsY()))
-            {
-                overlapY = tile.bottom - body.y;
+            body.overlapY = body.y - tile.bottom;
 
+            //  Distance check
+            if (body.overlapY > body.deltaY())
+            {
+                console.log('up overlapY', body.overlapY);
+                body.blocked.up = true;
                 body.touching.up = true;
                 body.touching.none = false;
             }
@@ -1050,10 +1065,12 @@ Phaser.Physics.Arcade.prototype = {
         else if (body.deltaY() > 0 && body.allowCollision.down && tile.tile.faceTop)
         {
             //  DOWN
-            if (body.bottom - tile.y < Math.ceil(body.deltaAbsY()))
-            {
-                overlapY = tile.y - body.bottom;
+            body.overlapY = body.bottom - tile.y;
 
+            if (body.overlapY < body.deltaY())
+            {
+                console.log('down overlapY', body.overlapY);
+                body.blocked.down = true;
                 body.touching.down = true;
                 body.touching.none = false;
             }
@@ -1061,40 +1078,38 @@ Phaser.Physics.Arcade.prototype = {
 
         //  Separate in a single sweep
 
-        if (overlapX === 0 && overlapY === 0)
+        if (body.touching.none)
         {
             return false;
         }
 
-        if (overlapX !== 0)
+        if (body.overlapX !== 0)
         {
-            // body.overlapX = overlapX;
-            body.x += overlapX;
-            body.preX = body.x;
+            body.x -= body.overlapX;
+            body.preX -= body.overlapX;
 
             if (body.bounce.x === 0)
             {
-                body.velocity.x = 0;
+                // body.velocity.x = 0;
             }
             else
             {
-                body.velocity.x = -body.velocity.x * body.bounce.x;
+                // body.velocity.x = -body.velocity.x * body.bounce.x;
             }
         }
 
-        if (overlapY !== 0)
+        if (body.overlapY !== 0)
         {
-            // body.overlapY = overlapY;
-            body.y += overlapY;
-            body.preY = body.y;
+            body.y -= body.overlapY;
+            body.preY -= body.overlapY;
 
             if (body.bounce.y === 0)
             {
-                body.velocity.y = 0;
+                // body.velocity.y = 0;
             }
             else
             {
-                body.velocity.y = -body.velocity.y * body.bounce.y;
+                // body.velocity.y = -body.velocity.y * body.bounce.y;
             }
         }
 
diff --git a/src/physics/arcade/Body.js b/src/physics/arcade/Body.js
index ac217b70..a7dd54ac 100644
--- a/src/physics/arcade/Body.js
+++ b/src/physics/arcade/Body.js
@@ -207,6 +207,7 @@ Phaser.Physics.Arcade.Body = function (sprite) {
     * For example allowCollision.up = false means it won't collide when the collision happened while moving up.
     * @property {object} allowCollision - An object containing allowed collision.
     */
+    //  This would be faster as an array
     this.allowCollision = { none: false, any: true, up: true, down: true, left: true, right: true };
 
     /**
@@ -214,12 +215,14 @@ Phaser.Physics.Arcade.Body = function (sprite) {
     * touching.up = true means the collision happened to the top of this Body for example.
     * @property {object} touching - An object containing touching results.
     */
+    //  This would be faster as an array
     this.touching = { none: true, up: false, down: false, left: false, right: false };
 
     /**
     * This object is populated with previous touching values from the bodies previous collision.
     * @property {object} wasTouching - An object containing previous touching results.
     */
+    //  This would be faster as an array
     this.wasTouching = { none: true, up: false, down: false, left: false, right: false };
 
     /**
@@ -310,6 +313,8 @@ Phaser.Physics.Arcade.Body = function (sprite) {
     */
     this.collideWorldBounds = false;
 
+    this.blocked = { up: false, down: false, left: false, right: false };
+
 };
 
 Phaser.Physics.Arcade.Body.prototype = {
@@ -370,8 +375,13 @@ Phaser.Physics.Arcade.Body.prototype = {
         this.y = this.preY;
         this.rotation = this.preRotation;
 
-        this.overlapX = 0;
-        this.overlapY = 0;
+        // this.overlapX = 0;
+        // this.overlapY = 0;
+
+        this.blocked.up = false;
+        this.blocked.down = false;
+        this.blocked.left = false;
+        this.blocked.right = false;
 
         if (this.moves)
         {
@@ -406,60 +416,56 @@ Phaser.Physics.Arcade.Body.prototype = {
     */
     postUpdate: function () {
 
-        if (this.deltaX() < 0)
+        // if (this.overlapX !== 0)
+        // {
+        //     this.x -= this.overlapX;
+        // }
+
+        // if (this.overlapY !== 0)
+        // {
+        //     this.y -= this.overlapY;
+        // }
+
+        if (this.deltaX() < 0 && this.blocked.left === false)
         {
             this.facing = Phaser.LEFT;
+            this.sprite.x += this.deltaX();
         }
-        else if (this.deltaX() > 0)
+        else if (this.deltaX() > 0 && this.blocked.right === false)
         {
             this.facing = Phaser.RIGHT;
+            this.sprite.x += this.deltaX();
         }
 
-        if (this.deltaY() < 0)
+        if (this.deltaY() < 0 && this.blocked.up === false)
         {
             this.facing = Phaser.UP;
+            this.sprite.y += this.deltaY();
         }
-        else if (this.deltaY() > 0)
+        else if (this.deltaY() > 0 && this.blocked.down === false)
         {
             this.facing = Phaser.DOWN;
-        }
-
-        /*
-        if (this.overlapX !== 0)
-        {
-            this.sprite.x += this.overlapX;
-        }
-        else
-        {
-            if (this.deltaX() !== 0)
-            {
-                this.sprite.x += this.deltaX();
-            }
-        }
-
-        if (this.overlapY !== 0)
-        {
-            this.sprite.y += this.overlapY;
-        }
-        else
-        {
-            if (this.deltaY() !== 0)
-            {
-                this.sprite.y += this.deltaY();
-            }
-        }
-        */
-
-        if (this.deltaX() !== 0 || this.deltaY() !== 0)
-        {
-            // console.log('dx', this.deltaX());
-            // console.log('dy', this.deltaY());
-
-            this.sprite.x += this.deltaX();
             this.sprite.y += this.deltaY();
-            this.center.setTo(this.x + this.halfWidth, this.y + this.halfHeight);
         }
 
+        // if (this.deltaY() !== 0 && this.blocked.up === false && this.blocked.down === false)
+        // {
+        //     this.sprite.y += this.deltaY();
+        // }
+
+        // if (this.deltaX() !== 0 || this.deltaY() !== 0)
+        // {
+        //     this.sprite.x += this.deltaX();
+        //     this.sprite.y += this.deltaY();
+
+        //     this.center.setTo(this.x + this.halfWidth, this.y + this.halfHeight);
+        // }
+
+        // if (this.deltaX() !== 0 || this.deltaY() !== 0)
+        // {
+            this.center.setTo(this.x + this.halfWidth, this.y + this.halfHeight);
+        // }
+
         if (this.allowRotation)
         {
             this.sprite.angle += this.deltaZ();
@@ -599,7 +605,7 @@ Phaser.Physics.Arcade.Body.prototype = {
     * Returns the delta x value. The difference between Body.x now and in the previous step.
     *
     * @method Phaser.Physics.Arcade.Body#deltaX
-    * @return {number} The delta value.
+    * @return {number} The delta value. Positive if the motion was to the right, negative if to the left.
     */
     deltaX: function () {
         return this.x - this.preX;
@@ -609,7 +615,7 @@ Phaser.Physics.Arcade.Body.prototype = {
     * Returns the delta y value. The difference between Body.y now and in the previous step.
     *
     * @method Phaser.Physics.Arcade.Body#deltaY
-    * @return {number} The delta value.
+    * @return {number} The delta value. Positive if the motion was downwards, negative if upwards.
     */
     deltaY: function () {
         return this.y - this.preY;
@@ -633,7 +639,7 @@ Object.defineProperty(Phaser.Physics.Arcade.Body.prototype, "bottom", {
     * @return {number}
     */
     get: function () {
-        return this.y + this.height;
+        return Math.floor(this.y + this.height);
     },
 
     /**
@@ -669,7 +675,7 @@ Object.defineProperty(Phaser.Physics.Arcade.Body.prototype, "right", {
     * @return {number}
     */
     get: function () {
-        return this.x + this.width;
+        return Math.floor(this.x + this.width);
     },
 
     /**