Warhammer 40000 The Rules for iBooksAs an alternative to its high-end, limited-edition codexes and rule books, Games Workshop has put out a new line of 40K digital reference material for iPads and iPhones. Warhammer 40,000: The Rules ($40) and 20 different Gamers Edition Codexes ($24 each) are available through Apple’s iBooks and contain all the rules and datasheets, cross-linked for easy reference during play.