Xess.io is a multiplayer, competitive take on the classic Chess game. You start with but a king. Use him to capture nearby neutral pieces to build yourself an army. But be weary of other players on the map. They're not your friends, and would rather crush you than allow you to be Chess-king.
As with the original version of the game, if you lose your king, you're dead. So while you have to use him at the start of the game to jump-start your army, be sure to protect him.
Much of the other rules are the same, as well. The Chess pieces all move in an expected manner. Bishops move diagonally, and rooks move in a straight line.
One of the other main big differences between this and the original Chess is that in Xess.io, is played out in real time, but you do have a timer to slow down your moves.
Conquer. If you have the biggest army, your king will be nice and safe behind it, which will allow your other pieces to do most of the work.