This is a classic! I always felt this was one of the best primers on the theory and practice of time travel available for any game.
It is fairly light on rules crunch (about 20 pages in the middle of a 90+ page book) and although there is a lot of discussion of time travel as it relates to the Timemaster continuity (Time Corps in the 75th century, Demorean alien bad guys), it is easy to retool as necessary. There are extensive examples of multiple timehopping and reasons/consequences for doing so, including "checking your work" and potential paradoxes. The section on Demorean tactics is useful in creating tricky time situations, and it also provides a rationale for why it doesn't devolve into a single endless cycle of "find break, fix, repeat" on the same event ad infinitum. In addition to using this for Timemaster, if you plan on running other time travel games like temporal probability Agency or Doctor Who, there is plenty here to make it worthwhile.