"n-Challenge" is the perfect puzzle game to test your skills and keep trained your mind, also reviewed by http://www.androidworld.it/, the most important website dedicated to Android in Italy.

Special feature: the Premium version is FREE if you invite friend (see below).

The GOAL is to have all the tiles in numerical ascending order, starting from the first row .

The RULES are simple:

- Initially you'll find the odd and even tiles on separate rows. You can only move the external tiles of the puzzle and only one tile at a time

- Each numerical tile can be followed by a tile of greater value

- Be careful! With advancing levels appear with increasing frequency some lock tiles that can be eliminated only if accompanied with other lock tiles in a blank row. You can move the lock tiles, but you can’t move the numbered tiles on a row containing a lock .

Other FEATURES:

* In-app tutorial with the puzzle game instructions
* Mute option for music and sound effects
* Option to sharing your score on Facebook

With the Premium Version you'll get more game levels and different backgrounds.

You can get the Premium version of this logic puzzle in two ways:

1) FREE inviting a friend. Enter his e-mail address on “Invite”: he receive a code, install the app and enter the code on “Help a Friend”. So the next time you’ll load the game you’ll get a free Premium Version!

or

2) Buying the app on Google Play store by clicking on “Buy”.

Are you still so sure of being able to count up to 15 ? To find out, you just have to try n -Challenge !