The Legend of Zelda
Even after 30 years, The Legend of Zelda is still one of the most successful and well-respected adventure games in gaming history. But the series is split cleanly into two styles: 2D and 3D. Both have been copied extensively. The structure and combat of the 2D games were mimicked constantly in the 8-bit and 16-bit eras, and still is today. The same can be said for the 3D games.
The dungeon structure and reliance on acquiring new weapons to proceed has found its way into modern games like Darksiders, which also uses the lock-on targeting system first introduced in Ocarina of Time. Of course, a series as influential as Zelda would inspire others but some, such as the recently released Ocean Horn, wear their influences on their sleeves, essentially copying the Zelda formula exactly.
