The Real ACT Guide 3rd Edition was released in 2011 and an update from ACT has long been overdue. The current edition of the official guide, also called the Red Book, has five full length practice tests. The problem is that the bulk of the tests are from old administration of ACT tests, for example the last two tests in the guide are from 2008 and 2009, and the first three tests are even older than those dates. In many ways the guide has become obsolete and ACT needs to release an updated version with at least ten tests, similar to the official guide for the SAT test.
ACT in one of its tweets announced that it plans to update the Real ACT Prep Guide sometime next year in 2016. The exact date has not been announced yet.