Do you know the Hippopotamus Defence. It is a series of irregular chess opening systems in which Black moves a number of pawns to the sixth rank, and keeps his pieces on the seventh rank. Many experts considered it basically losing, but it has maintained a solid fifty percent for Black, even at the highest level of competition. In the British Chess Magazine Raymond Keene reviews the book The Hippopotamus Defence by Italian IM Alessio de Santis on the subject. | Picture Samuele Giglio, Unsplash