var Frog = Container.expand(function () {
	var self = Container.call(this);
	var frogGraphics = self.createAsset('frog', 'Frog character', .5, .5);
	self.jump = function () {
		self.y -= 100;
		self.gravity = 2;
	};
	self.dodge = function () {
		self.x += 100;
	};
});
var LilyPad = Container.expand(function () {
	var self = Container.call(this);
	var lilyPadGraphics = self.createAsset('lilyPad', 'Lily pad', .5, .5);
	self.move = function () {};
});
var Danger = Container.expand(function () {
	var self = Container.call(this);
	var dangerGraphics = self.createAsset('danger', 'Danger', .5, .5);
	self.move = function () {};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	var frog = self.addChild(new Frog());
	var lilyPads = [];
	var dangers = [];
	frog.x = 2048 / 2;
	frog.y = 2732 / 2;
	LK.on('tick', function () {
		frog.y += frog.gravity;
		for (var i = 0; i < lilyPads.length; i++) {
			lilyPads[i].move();
			if (lilyPads[i].x < -50) {
				lilyPads[i].destroy();
				lilyPads.splice(i, 1);
			}
		}
		for (var i = 0; i < dangers.length; i++) {
			dangers[i].move();
			if (dangers[i].x < -50) {
				dangers[i].destroy();
				dangers.splice(i, 1);
			}
		}
	});
	stage.on('down', function (obj) {
		var event = obj.event;
		var pos = event.getLocalPosition(self);
		if (pos.y > frog.y) {
			frog.jump();
		} else {
			frog.dodge();
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -2,8 +2,9 @@
 	var self = Container.call(this);
 	var frogGraphics = self.createAsset('frog', 'Frog character', .5, .5);
 	self.jump = function () {
 		self.y -= 100;
+		self.gravity = 2;
 	};
 	self.dodge = function () {
 		self.x += 100;
 	};
@@ -25,8 +26,9 @@
 	var dangers = [];
 	frog.x = 2048 / 2;
 	frog.y = 2732 / 2;
 	LK.on('tick', function () {
+		frog.y += frog.gravity;
 		for (var i = 0; i < lilyPads.length; i++) {
 			lilyPads[i].move();
 			if (lilyPads[i].x < -50) {
 				lilyPads[i].destroy();