This game, called Kaxo, was invented by Alex Voak, a student at the King's School in Ely.
Kaxo is a real challenge! Two players who take turns crossing out dots using vertical, horizontal, and diagonal (45 degree) lines. They can also choose to cross out a single dot. Lines must not pass through each other, or any dots that have previously been crossed out. The player who crosses out the last dot loses. (You can see Alex explaining the rules in the video below.)
Have a go at playing the game, either against the computer, or against a friend (choose 1 player or 2 players).
If you can't find a winning strategy, why not try reducing the grid size or work backwards from a completed game?
In the video below Alex explains the rules of the game and discusses how to play it.