Beings with powers that manipulate time itself, chronothurges, first appeared in The Genius Guide to the Time Thief and The Genius Guide to the Time Warden. Each of those books presented a new base class (time thief and time warden, respectively) that had access to two new powers sources, "motes of time" and "aevum." They also offered hints of a world where a war waged through multiple, linked, parallel timelines and time itself could be stolen, damaged, or even destroyed.
The classes immediately garnered a large following, and requests for additional material quickly began making their way to Super Genius Games. The first book to offer additional support for them was Rite Publishing's 101 Renegade Class Feats, which includes 7 feats designed specifically for use by the time thief, as well as feats for numerous other classes created by Super Genius Games and other publishers. Later we released Mythic Menagerie: Ravagers of Time, presenting 7 time-themed critters to give a GM a range of chronal allies and opponents for a campaign with temporal elements, and #1 With a Bullet Point: 7 time Thief/Time Warden Feats, which gave a few expanded options.
Now Genius Options: Masters of Time expands the classes and time-themed powers even further, with new ideas for chronothurges of many different types and classes, an outline on how timelines work (adapted from Ravagers of Time), rules for using chronothurge abilities to create temporal monsters, new ways for characters with non-chronothurge classes to gain some temporal powers, and feats for time-manipulators of any type.