The digits game.
It's addictive and yet it's simple, really.
Cross out pairs of digits that are either the same, or amount to 10 when added.

Doodle Digits (aka uDigits) is a different game for lovers of numeric puzzle games, like Sudoku. It is novel and very easy to play. The idea is simple: in as few moves as possible, match and cross pairs of digits that are the same or equal to 10 when added.

Sounds simple? However, the match can occur only if two digits are in certain locations on the field. But where exactly, depends on the selected skill level.

Pro:
two digits are next to each other horizontally (they follow one another, either on the same row or wrapping to the next row), or vertically

Advanced:
two digits that are the first uncrossed and the last uncrossed digits on the field. Plus the rule from Pro.

Beginner:
the two matching digits are located diagonally, but only on consecutive rows. Plus the rules from Advanced and Pro.

You will be surprised how a game this simple can be so addictive.