An intriguing and challenging Japanese puzzle game. As per the Wikipedia article, describing FUTOSHIKI rules:

Your goal is to place the numbers, such that each row and column contains only one of each digit. Some digits may be given at the start. Inequality constraints are initially specified between some of the squares, such that one must be higher or lower than its neighbor. These constraints must be honored in order to complete the puzzle.

Good luck!

Game Controls: Mouse

Game Credits: Tomas Rychnovsky, Petr Visek, Juraj Ruzicka