"xess.io" is a chess game but not for two as everybody used to. In "xess.io" you can fight with multiple players on the same chessboard. You will build up your army by eating the white chesspieces which don't belong to anyone, as soon as you feel that you've eaten more than enough, you can go to war with your nearest opponent. The target is to eat the King of your opponent and then all of his chesspieces come under your reign. But keep in mind that you have to protect your King, as the rule, under which you can eat chesspieces of opponents, applies to yourself as well!
In order to move your piece press and hold the left mouse button and drag it towards the opposite side of the board following the general rules of chess game for each piece.