Entanglement is a game that has gained a fair bit of popularity lately.
You are given a hexagonal tile with six paths printed on it, with two path ends touching each side of the hexagon. One such tile is as follows:
You may rotate, but not move the hexagon that has been provided to you.
Once you have selected an orientation of the hexagon, a path is traced along that hexagon, and you are provided a new hexagon that you may rotate at the end of your current path.
The goal of the game is to create the longest path possible without running into either the centre hexagon or the outer edge of the game board.
It seems very simple at first glance. But give it a try and you'll see just how challenging it can be.