Chess mentor demo
Having recently joined chess.com, I checked out the chess mentor demo and was surprised to find that Be4 is not acceptable in position given below. The message I received was "Incorrect Move... Use all three of your pieces. That includes your king!" I don't know whether you checkmate in fewer moves with Ke3, which is the move chess mentor was looking for, but it is clear to me (having played the position against Fritz) that 1. Be4, Kg5 2. Be5 will--followed by the use of the king, of course--also mate black shortly. Why force one correct path upon the users of chess mentor when there is more than one way to win? Maybe Ke3 is the path given by some tablebase, but nobody plays chess as accurately as the tablebases.