text: In addition to weapons, Ratchet gains many gadgets with varying uses. Some gadgets are necessary to travel about some levels, such as "Grind Boots" that allow Ratchet to grind on rails, or a "Swingshot" (portable, reusable grappling hook) that allows him to grapple a target and swing across gaps. Other gadgets can be used in combat as a means to distract foes, and others are needed to unlock certain doors and thus continue missions; in these cases, the player typically must solve a puzzle minigame in order to successfully use the gadget and unlock the door.
  Each game is broken down into a series of missions that take place on numerous planets across the galaxy. While most objectives must be completed in a certain order to progress the main story, other objectives are optional but can lead to useful rewards. Once the player has completed a mission on a planet, they can typically return to any previous planet they have visited to attempt missions they could not complete before. In addition to objectives based on platforming and weapon elements, missions may include minigames such as various races and arena combat. Typically, one or two of these minigames must be performed as part of the main story, but further optional challenges can be done to earn greater rewards, typically in the form of "bolts", the unit of currency used throughout the game. There are also missions that focus on Clank, often controlling a set of smaller robots called Gadgebots to travel through areas that Ratchet cannot. Clank's gameplay sections in mainline titles after Tools of Destruction are also considerably more experimental in their gameplay mechanics.