Sudoku Infinite by LukaszM is a game about solving randomly generated sudokus.

How to Play

Tap on a numbered button on the bottom to select it, tap outside the grid and buttons to deselect the numbers, tap on an unoccupied cell with a number selected to place the number, tap on a nongiven number with a different number selected to replace the number, tap on a nongiven number on the same number to delete it. Tapping on the 3x3 square button toggles the pencilmarking mode, which pencilmarks the number if you tapped an empty cell with a selected number. The X button allows you to just delete any number with 1 tap. Tap on a cell with a pencilmark with the same number to remove it. Be warned, pencilmarks automatically remove if the placed digit sees the pencil mark, even if it is incorrectly placed. Place all digits without repeating a digit in its row, column, or box to win. In sudoku X, theres an added condition that digits might not repeat in the 2 indicated diagonals.

Techniques

Since puzzles are randomized, there isn't a predertermined solution, however there are some techniques you can use that help you solve the puzzle:

Hidden Single

In general, if there is only 1 position a digit can go without conflict, then that digit goes there, otherwise the puzzle will break. This technique is mostly used in boxes.

Filling a Set

In consequence to the 1st technique, if you see a set of all but 1 digits in a row/column/box/diagonal, then the set can be completed in only 1 way.

Naked Single

If theres only 1 possible digit to place in a single cell, then it is a naked single, and can be placed.

Pencilmarking

You can use pencilmarking to keep track of possible canidates to note of when it dwindles to 1 possible placement / number.

Pairs

If 2 cells have only 2 of the same possibilities of valid digits left or are the only 2 cells with valid positions left for the 2 digits, then it makes a pair, removing some options for other cells or/and displacing some digits out of the cells.

Roping

In any puzzle that isn't a 9x9, roping is present, meaning a number on the bottom part of box on the left will all appear on the top of the right, and vice versa.