Trap Cards and Quick-Play Spell Cards which activate during the Battle and Damage Steps tend to be some of the most common cards used by players, and the "Ancient Gear" archetype focuses upon preventing your opponent from using them. The concept of having limited Spell and Trap immunity is similar to the Duelist Kingdom arc of the second series anime, where Machine-Type monsters were immune to magical attacks.
"Ancient Gear Gadjiltron" monsters share a relation with the "Gadget" archetype, gaining additional effects when "Red", "Green" and/or "Yellow Gadget" are Tributed to Summon them.
The humanoid "Ancient Gears" bear a striking similarity to Ancient Greek soldiers, and so their creation may be linked to the Antikythera mechanism.
Most "Ancient Gear" monster possess an effect that prevent the opponent from activating any Spell/Trap Cards until the end of the Damage Step when they attack. This allows "Ancient Gear" monsters to attack without fear of being stopped by any Spell/Trap Cards. However, "Ancient Gear" monsters do not stop Monster Effects. A number of cards allow "Ancient Gear" monsters to be Summoned from the Deck, such as "Spell Gear" and "Machine Duplication". Most "Ancient Gear" monsters possesses high Levels so they require Tributes to Summon. Cards such as "Geartown" and "Ancient Gear Castle" allows ease of Tribute Summoning "Ancient Gear" monsters. "Cyber Dragon" can also give some ease of Tribute Summoning "Ancient Gear" monsters. "Ancient Gear Workshop" is also recommended if you use "Ancient Gear Golem" and "Ancient Gear Beast", as they cannot be Special Summoned.
Finally, being Machine Monsters, they are especially vulnerable to "Chimeratech Fortress Dragon", which can allow your opponent to clear your field and gain a 2000+ ATK beatstick. For this reason, you should never leave a "Cyber Dragon" on your side of the field whilst you control another machine. It may also be wise to add "Battle Faders" to your deck to prevent your opponent from attacking directly, as well as giving you tribute fodder for the higher level Ancient Gears. Combine this with cards that change battle positions such as "Enemy Controller" or reduces ATK such as "Shrink" and you could easily turn the tables to your favor.