There are two main groups of "Gadget" cards. The first is the colored "Gadgets", used by Yugi Muto, which act as generic Machine support. The second group, used by Leo, supports the "Morphtronic" archetype. The remaining "Gadgets" are not part of either group.
The most common way to play "Gadget" archetype is to use it with "Machina" cards. A Machina Gadget deck focuses on bringing out "Machina Fortress" on to the field, generating a constant stream of Gadget monsters through "Red", "Green" and "Yellow Gadget" and maintaining advantage over the opponent. With the advent of "Gold Gadget and Silver Gadget, the player can get another "Gadget" monster on to the field more quickly.