Sudoku variable size, icons and difficulty.
No ads and completely free.
also available as a Web site: http://timsp.de/sudoku/


Features:
Arbitrary size from 4x4 (Block: 2x2, 16 fields) without limitation, tested up to 30x30 (Block: 6x5, 900 fields). Even with non-square blocks such as 3x2 or 5x4.

Arbitrary symbols, either classic with numbers, clear letters or playing with smileys. In addition, custom symbols can be used, thus the creativity knows no bounds (for example, Roman numerals, animal Emoji, Greek alphabet).

Selectable difficulty of dissolved to heavy (free by number of fields).


all
Through many settings Sudokus for each, e.g .:

Children:
Simple Sudoku with fewer fields and symbols instead of numbers.

Beginner:
Classical 9x9 Sudoku with numbers.

Experts:
Large Sudoku with many free fields.


Open Source
Source code on https://github.com/timsp97/sudoku
Solution algorithm: https://attractivechaos.github.io/plb/kudoku.html
Framework: https://vuejs.org/
Android app created with PhoneGap Build

Icons made by Freepik (http://www.flaticon.com/authors/freepik), Gregor Cresnar (https://www.flaticon.com/authors/gregor-cresnar), Dave Gandy
(Http://www.flaticon.com/authors/dave-gandy), Egor Rumyantsev
(Http://www.flaticon.com/authors/egor-rumyantsev), Hanan
(Http://www.flaticon.com/authors/hanan) from www.flaticon.com is licensed by CC BY 3.0.