You have to have two people for chess. Why not have two people for sudoku? Websudoku is the world's greatest multiplayer sudoku game. You can send requests to other users, play single player with 5 very awesome modes, or play wild card, and make new friends while developing epic skills. Get off social media, and get on playing websudoku.

Github Page: https://github.com/thejavamonster/websudoku

Website: https://websudoku.me