Kaeru no Tame ni Kane wa Naru

Kaeru no Tame ni Kane wa Naru, officially translated as The Frog for Whom the Bell Tolls, is a Game Boy action-adventure game released in 1992 only in Japan. While not officially part of the Legend of Zelda franchise, the game was heavily influenced by it, and in turn influenced later games in the franchise, most directly The Legend of Zelda: Link's Awakening (which runs on the same engine) and Freshly-Picked Tingle's Rosy Rupeeland. It acts as a satire of both Zelda-style action-adventure games and traditional RPG games.

Plot
The Princes of the Sablé and the Custard Kingdoms have been rivals since childhood. The Sablé Prince, who is the protagonist, always loses in friendly combat against the Custard Prince, Richard. One day, a message arrives that the marauding Geronian army has invaded the peaceful Mille-Feuille Kingdom and attempted to capture its princess, Tiramisu. The two rush off to save the day, but Richard manages to stay one step ahead. After attempting to storm the occupied castle, The Sablé Prince learns that the princess, followed by Richard, managed to escape into the confusing forest to the east, and he in turn travels there. He finds the lair of the legendary witch, Mandola, led there by her pet vulture Polnareff. She offers a potion she previously gave to Richard, and he drinks it. After chasing a thief named Jam and falling down a well, however, the prince finds himself turned into a frog.

The froggified prince returns to the castle town, where he finds Richard and his soldiers also turned into frogs. The Sablé prince uses his form to explore the castle further, as the Geronians like frogs. However, he then learns that the reason for it is that their king, Delarin, is actually a snake who enjoys eating frogs. Believing Mandola tricked them, the Sablé prince opts to find Mandola and force her to change him back. Once he finds her, she gives him another potion, which allows him to turn into a human after fainting, a frog after falling in cold water, and a snake after eating a snake egg. Mandola tells him the original potion would have worn off once spring arrived, with her plan being to use the frog-transformed army to infiltrate the castle, ambushing the Geronians once the spring bell is rung. The Sablé prince goes off to find the spring bell, but finds it was broken in an earthquake and can only be fixed for the same ridiculously expensive price he spent on the second potion.

The Sablé prince then travels across the land to attempt to get the funds to do so, meeting such characters as the gold-mining Japanese businessman Alfred Jinbe, picky-eater and inventor Dr. Arewo Stein, shy shopkeeper Little Red Riding Hood, and the alcoholic miner Heske and his "Kazan All Stars" digging crew. Once the funds are secure and the bell begins to be fixed, the Sablé prince infiltrates the castle one last time to find and defeat Delarin. Delarin turns from a normal snake into a giant monster snake that begins to effortlessly defeat the prince. However, he is helped by Dr. Arewo Stein in a giant robot suit, Richard and his army (who are eaten right before being turned back into humans to attack his insides), and Alfred Jinbe (who throws a dagger into Delarin's eye). Once Delarin is defeated, Mandola appears and reveals she was the missing Princess Tiramisu in disguise all along, with Alfred Jinbe being Polnareff, actually her military's commander, who made the entire convoluted plan as a way to beat the Geronians. Richard then reveals he was in on the plan as well. After a final fencing duel between the Sablé prince and Richard, the Sablé prince finally wins, and Richard sets off to parts unknown. The Sablé prince and Tiramisu prepare to get married, only for the former to be dismayed to learn she has the same personality as the sneaky, manipulative Mandola.

Influence from the Zelda series
Kaeru no Tame ni Kane wa Naru has notable traits in common with the previous Legend of Zelda games, notably its top-down perspective and map structure, character sprites (which resemble downscaled The Legend of Zelda: A Link to the Past sprites), sword and shield upgrades (including an appearance from the Mirror Shield), other equipment (a pair of wristbands and a "Hyper Glove" act as substitutes for items such as the Power Bracelet and Power Glove), and miscellaneous items (such as the Life Stone, which resembles a Heart Container in design and function, and the Kaifuku Wine, which acts as Life Water). A stand-in for the original Lost Woods, called「ババロア山」(Babaroa Yama, "Bavarois Mountain", a play off baba, meaning "hag", and "") appears early in the game, with the Sablé prince commenting that he has seen such a puzzle before. A common obstacle in the sidescrolling areas of the castle interior acts just like Bubbles do in Zelda II: The Adventure of Link.

Influence on later Zelda games
Unlike most other Zelda-inspired games, Kaeru no Tame ni Kane wa Naru recursively influenced later entries in the series, primarily due to many members of the development team returning. The most direct influence the game has on the Zelda games is in The Legend of Zelda: Link's Awakening, which is somewhat a successor to it. The two games run on the same engine and many sound effects and minor graphics (notably the font) are directly reused. The character of Richard appears as a cameo, with his house being full of frogs using sprites from the original game and the background music using the game's primary riff. In The Legend of Zelda: Ocarina of Time, Princess Zelda's role as Sheik takes several cues from Tiramisu's role as Mandola, while in The Legend of Zelda: Oracle of Ages, Ralph acts as a less-competent counterpart to Richard's original role. The combat system, in which the Sablé prince gets into a cartoon-style "dustcloud fight" with his opponent, losing health at different intervals, was later reused and expanded for Freshly-Picked Tingle's Rosy Rupeeland.