Wild Mastermind : color matrix

Break the secret code! 

This is a complex variant of the mastermind logic board game, where only the "easy" level is similar to traditional mastermind.
In this version each "position" can contain 1-3 colors in a vertical column (1-3 depending on the difficulty chosen i.e. the number of rows).

When starting a new game, the phone selects a random combination of colors for the secret code. Through guesses and responses, the goal now is to reveal the secret in as few attempts as possible.

Rules:
As in traditional mastermind the answer-pegs are:
Black: guess has correct "item" in the same position as the secret code
White: guess has correct "item" in a wrong position compared to the secret code.

In traditional mastermind an "item" would be a single color only (this is the "easy" version of this game, with only one row).
The other levels add more rows, and an "item" now becomes composed of more than one color (vertically, having a distinct shape fore each row).

In this version the number of rings in the black or white answer-peg yields the number of rows matched for that peg. A solid peg (black or white) is given when all rows are matched.
An "item" in the guess (there are four of them) is always matched against, at most, one single "item" in the secret code. 
To avoid ambiguity more rings are preferred to less and black is preferred to white on same number of rings, if several matchings are possible.

Gameplay:
Tap the locations for colors to toggle through them, or tap an earlier guess to pick that color. 
Long-tap and drag to copy an existing color to a specific location. 
Double-tap an earlier guess (background) to copy all colors to current.
When ready tap the green arrow to get a reply and move on to the next guess.
It is possible to "fix" a guess into always staying visible by clicking thumbtack.

A "cheat" mode is added to allow going on with "unfinished" guesses containing empty spaces and doubling number of available guesses.

The game now has an extra mode "solve-challenge" where you start on the final attempt to try to solve.