“Region Select” is a new puzzle game for Android discovered by Osaka City University Advanced Mathematical Institute using advanced mathematical knot theory. Although its rules are as simple as Sudoku and Rubik’s Cube, “Region Select” will challenge you to think ahead like Japanese Go.[Game explanation]At the beginning there is a knot figure. The spaces between the lines are called “regions”, and the places where the lines meet are called “crossings”. Each crossing has a “lamp” which can be turned on or off by clicking on the region bordering it. But when you click on a region, all of its crossing lamps change! If a lamp is already on, it will be turned off, and if a lamp is off, it will be turned on. The goal of the game is to light up all of the knot’s lamps by clicking on different regions. Mathematical knot theory proves that each knot figure can be cleared. [About knot theory]Knot theory is a branch of mathematics studying tangled string knots to determine such things as whether a knot is actually tied or untied, how a knot can be untied, and what kinds of knots exist, etc. Nowadays knot theory is studied and used around the world not only in mathematical research but also in physics, chemistry, and biology, etc. 【Music provided：tomoya】Look forward to updates with more knots coming soon!