Assassin's Creed Syndicate was the first game in the main series to introduce a playable grappling hook.
The grappling hook is a device used by Jacob and Evie Frye to reach rooftops and cross gaps quickly in Victorian London. It supports the game's faster movement through a dense city, where broad streets, elevated railways and tall buildings make vertical traversal especially important.
Syndicate was released in 2015 and is set during the Industrial Revolution. The hook does not replace parkour; instead, it supplements climbing by allowing the twins to create rapid ascents and short horizontal lines between buildings. The game also features a horse-drawn carriage system for movement at street level.
The device is sometimes associated with later entries because similar traversal tools became common in action games. In Assassin's Creed, however, Syndicate is the key main-series introduction. Unity, released the year before, used familiar climbing and parkour mechanics without this grappling-hook system.