Bulls and cows /Guess a number Android game

Bulls and cows is also known as Mastermind, 4digits, guess the number puzzle game. The goal of the game is to guess the opponent's secret number with a minimum number of suggestions.
In the beginning of the game you enter your secret number and android generates a random number, too. Digits in the number can't be duplicated.
In turn, players try to guess their opponent's number. The opponent responds by announcing the number of matches.
If the matching digits are on their right positions, they are "bulls", if they are on different positions, they are "cows".

Example:

Secret number: 8561
Opponent's try: 3518
Answer: 1 bull and 2 cows. (The bull is "5", the cows are "8" and "1".)

The first person to reveal their opponent's secret number wins the game.
The game can be made more challenging by using five-digit or six-digit secret numbers.

Features:
* Ability to choose count of digits in secret number - 3, 4, 5 or 6
* Ability to choose whether to play with leading zero in numbers
* Hints in the game play
* Draft
* Game history
* Game themes (Dark ocean green, light ocean green, dark blue, orange, pink)
* Vibration on button touch
* End of game sound effects