Chess opening are so complex and theoretical that amateur players will have trouble understanding them. An example is the Perenyi Attack of the Sicilian Defense (see diagram) which yields an immensely complicated and tactical position that even strong players have difficulty handling, and that is beyond the comprehension of most amateurs. Major changes in the rules of chess in the late fifteenth century increased the speed of the game, consequently emphasizing the importance of opening study. Thus, early chess books, such as the 1497 text of Luis Ramirez de Lucena, present opening analysis, as does Pedro Damiano (1512), and Ruy López de
SpongeBob Moves In! App Store. For the week ending July 1, 2013, the game ranked at #6 at the App Store Official Charts of Top Paid iPhone Apps, and on #4 at the Top Paid iPad Apps. The following week, the game was ranked at #5 at the Top Paid iPad Apps. "SpongeBob Moves In!" received mixed to positive reviews from critics, mainly due to the in-app purchases that are expensive. Peter Willington of "Pocket Gamer" said "I do still love the music, and it's clearly the best aspect of the game - but if that's what you're after then you're probably better