Kaodoku

Kaodokus are a new variation of sudoku with symbols that are only partially given. Originally invented for Belgian Mensa magazine Commensal, kaodokus offer a lot more variety than ordinary sudokus. Instead of numbers, the cells contain smiley faces which can have three possible shapes and three possible mouths. Each of the nine unique combinations has to appear exactly once in each column, row or other marked area just like in a normal sudoku. The big novelty is that in some cells only the mouth or shape is given, leaving the missing part for you to find. You can even ask for grids that initially don't include a single full symbol! This makes the puzzle experience a lot richer, requiring complex strategies combining bits and pieces of information in original ways.

Features:
- Normal grids completely free, with as many randomly generated puzzles as you like in many different levels of difficulty.
- With a single in-app purchase, you can unlock more complex puzzles with extra diagonals, gray squares and chaotic grids which require even deeper thinking combining all those intersecting regions.
- Sophisticated hint system which actually suggests possible ways forward using step by step logic. Especially in the beginning this is very helpful since even the easiest kaodoku grids can be daunting for those not used to them.
- Activate pencil notes in the settings so you can zoom in and freely draw whatever doodles you like, just like you would on paper.
- Alternatively, you can also use standard candidate marks to keep track of the possible symbols in each cell. In very difficult puzzles, the hints function will take these candidate marks into account if they are the only way of making progress.
- Share puzzles with others, export them in pdf or png format, or print them on paper to solve them the old-fashioned way. Feel free to publish puzzles in magazines or on websites, as long as you don't remove the kaodoku web address.