1. threatened squares: Displays the status of each piece on the board. A red square means that the piece is under attack and not sufficiently defended  or that it is being attacked by a piece of lesser value. This is usually a pretty serious danger signal and means you must take active measures to avoid losing a piece. Yellow means that the piece is under attack  but it is just sufficiently defended. You must be careful about removing any defending piece. Green means the piece has enemy contact but is well defended. Usually it is okay to remove a defending piece. 2. Engine vs Another Engine make it possible for two different chess engines to play with each other. its better than one engine vs itself!
January 27 2017