"Chrono Trigger" features several other distinct gameplay traits, including time travel. Players have access to seven eras of the game world's history, and past actions affect future events. Throughout history, players find new allies, complete side quests, and search for keynote villains. Time travel is accomplished via portals and pillars of light called "time gates", as well as a time machine named "Epoch". The game contains twelve unique endings (thirteen in DS, iOS and Android versions); the ending the player receives depends on when and how they reach and complete the game's final battle. "Chrono Trigger DS" features a new ending that can be accessed from the End of Time upon completion of the final extra dungeon and optional final boss. "Chrono Trigger" also introduces a New Game Plus option; after completing the game, the player may begin a new game with the same character levels, techniques, and equipment, excluding money, with which they ended the previous playthrough. However, certain items central to the storyline are removed and must be found again, such as the sword Masamune. Square has employed the New Game Plus concept in later games including "Chrono Cross" and "Final Fantasy XV" among others.