Time Police

　タイムレンジャー鑑賞中ということもあって、タイムトラベルものを検索してみました。以外と時間警察ズバリなものはないのに驚きました。時間旅行についていろいろ総論的にまとめたサプリメントが多い印象です。その中で取り回しが割とよさげなものが次のもの。d20系列のミニゲームです。
　E.N. Mini-Games - Time Police - EN Publishing | DriveThruRPG.com
　

Time Police originally appeared in EN World Gamer Issue 3: The Unpublished Issue.

Play a time cop, a chronologist or a period actor, travel back in time and fight villains intent on committing crimes throughout time!

Time Police is a d20 mini-game designed to let you and your gaming group try something different for a quick session, with the option of developing into a more long-term campaign. Time travel is one of the most classic elements of science fiction, and its mind-bending ability to mix anachronistic elements into the same story has the potential for memorable adventures. Crime in time is just the basis for this mini-game, and we encourage you to use this book to play all manner of time travel games.

In the year 2163, the government of the United States of North America began work on Project Mercury, a top-secret program intent on sending a human being back in time. After decades of struggle, in the year 2196, scientists were able to open a window into the past and a mechanical probe managed to enter and return safely. Further tests were scheduled involving animals, and eventually human beings, but that schedule soon got rewritten. On May 8, 2196, the President of the United States of North America was assassinated by agents of a hostile government. Priorities were instantly changed, and despite the lack of testing, a Special Forces unit was deployed through the time portal to stop the assassination. The Special Forces managed to complete their mission, and the president’s life was saved, but when they returned to their own time, they made a disturbing discovery: the president was still dead. Teams were sent again into the past, where it was confirmed that the assassination attempt had failed. There was only one explanation: the past could not be changed, even by changing the past. It was theorized that the “time machines” were actually creating new alternate dimensions, rather than transporting people back in time. Regardless of the explanation, Project Mercury was scrapped.

　「時間旅行によって新たな時系列≒並行世界が発生するので、過去を変えても現在は変えられない」という理屈になっているので、厳密にはいわゆる時間警察ではないような気もしますけど、D20モダンなら一応日本語版もあるし安価なのでポチ。