GAME CENTER !!!!!!!, 22 Leaderboards. - Five levels of difficulty. - Four appearances are available to be selected. - Pause/Resume. - Smart note, Auto note. - Automatically check for incorrect numbers. - Keep device from sleeping, your iPhone/iPod and iPad no longer sleep while you are thinking a puzzle. - Compatible with iOS4.x/5.x iPod, iPhone device, Retina Display for iPhone 4 and iPad support. Any reviews and ratings are all appreciated, your comments are making this app become better!!