A very simple puzzle game in terms of the premise, but a simple premise does not mean that the solutions are simple. The combination of arithmetic and Sudoku is a fascinating and works marvelously. This game really had the gears turning in my head. I also love just how relaxing this is, and it is never too frustrating either. I'm glad that this is a demo because that means that there will be more, and I simply cannot wait to solve more puzzles. This is a game that I will definitely come back to in the future whenever I need to wind down and relax.