The goal is to make the sum of numbers in each row and column be equal to the number in the box.
What you have to do is to remove some numbers from the equation by clicking on them.
It sounds simple but requires a lot of thinking.
The board sizes range from 5×5 to 8×8. There are also 3 levels of difficulty: 1-9, 2-4 and 1-19.
1-9 means the numbers to calculate will range from 1 to 9.
There are 2 game modes: Classic and Endless.
In Classic mode you can choose which board size and difficulty you want to play
In Endless mode you will be given a puzzle with random size and difficulty.
Your total wins in any mode is saved.
You can compete in the leaderboards using a Facebook login.