Time travel books are one of those genre-bending subgenres of science fiction that could easily be fantasy. It's certainly Speculative Fiction.
Time Travel Science Fiction features stores where time ...
The Ark of Time was just released in Dec 2014. The premise is that Earth has been taken by aliens, and a bunch of egghead scientists decide to go back in time to snatch people just before they die so they can create an army in the future to retake Earth. This is a well-thought-out plot full of action and twists, and a great page-turner. It even will stimulate your thoughts about time, reality and religion. I recommend it highly.
Excellent book--mostly action sequences but also some deep thought and interesting historical facts. Buy it and and you'll love it!