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
Tactical role-playing game planned MMORPG that would have featured tactical combat, had development not been cancelled in 2006. "Gunrox" (2008), "Poxnora" (2006) and "Wakfu" (2012) are some other recent examples. Many tactical RPGs can be both extremely time-consuming and extremely difficult. Hence, the appeal of most tactical RPGs is to the hardcore, not casual, computer and video game player. Traditionally, tactical RPGs have been quite popular in Japan but have not enjoyed the same degree of success in North America and elsewhere. However, the audience for Japanese tactical RPGs has grown substantially in the West since the mid-90s, with PS1 and PS2 titles