var bootState = {

    create: function () {

        //Initial GameSystem (Arcade, P2, Ninja)
        game.physics.startSystem(Phaser.Physics.P2JS);

        //Initial Load State
        game.state.start('load');
    }
};

var bootState = {

    create: function () {

        //Initial GameSystem (Arcade, P2, Ninja)
        game.physics.startSystem(Phaser.Physics.ARCADE);

        //Initial Load State
        game.state.start('load');
    }
};

--- 
+++ 
@@ -3,7 +3,7 @@
     create: function () {
 
         //Initial GameSystem (Arcade, P2, Ninja)
-        game.physics.startSystem(Phaser.Physics.ARCADE);
+        game.physics.startSystem(Phaser.Physics.P2JS);
 
         //Initial Load State
         game.state.start('load');
Change physics engine to P2
