TileSlider Challenge app for iPhone and iPad

This game is about rearranging numbers from 1 to 15 by sliding them. Game is completed when user orders them properly.
User interface is intuitive. When the game opens, it starts with complexity level 1. User can increase complexity level by pressing button "More complex".

User can challenge friends for a game through Facebook or Mail. Once user plays and finishes the game, a alert view will appear with buttons to 1)start a new game, 2)Challenge @ Facebook 3)challenge @mail 4) cancel. User will tap on a button and if required authorizations( for Facebook and mail) to tell their friends about the game with key/code and score. Users friends who are interested in the game copy the game key/code.

Once challenged, user can create the game copying the game code in "Take Challenge" screen. Users will enter the screen where they has to enter a game code/ game key, only when someone challenges them with a game code / game key. This challenge can done through Mail/Facebook.
A sample game code is : 0_1_2_4_5_6_3_8_9_10_7_11_13_14_15_12_1_15. User needs to enter that code in Text field to generate the same game challenger has played.