In a fast-acting novel, the protagonist would travel to different worlds to complete different missions or experience different lives in a loop. The following are some common worlds: Love at the End of Time: The protagonist travels to a world similar to the movie "Time Lovers" and continuously travels to different time and space to complete the characters in the movie and experience different lives. 2 Sin City: The protagonist transmigrated to a game world similar to Sin City and played different roles in the game to complete different missions to find the truth. 3. Travel to the White Night Journey: The protagonist travels to the novel White Night Journey by Keigo Higashino and continuously travels to different times and spaces to solve the mysteries in the novel. Save Harry Potter: The protagonist travels to a world similar to the movie Harry Potter to help Harry Potter complete his mission to protect the magical world. Wheel of Time: The protagonist travels to a sci-fi world similar to the Wheel of Time. In this world, the protagonist constantly travels to explore the secrets of the future world. The above are some common worlds where the protagonist will encounter different characters and plots and experience different life experiences.