Nazo Puyo Arle no Roux (なぞぷよ アルルのルー; also mistakenly referred to as transliterations Nazo Puyo: Aruru no ruuu and Nazo Puyo: Aruru no Ru) is a puzzle game developed by Compile for the Sega Game Gear and released exclusively in Japan in 1994. Despite being the third game in the Nazo Puyo subseries, it is drastically different from its prequels, taking a combined RPG/puzzle approach to its (now existent) storyline. It would receive two sequels, both on the Super Nintendo Entertainment System (Super Nazo Puyo Rulue no Roux, combining a retooled version of this game with a new story mode focusing on Rulue, and Super Nazo Puyo Tsu: Rulue no Tetsuwan Hanjouki, a new game focusing exclusively on Rulue).

Nazo Puyo, the primary gameplay mode, has the player solving preset puzzles. Unlike previous Nazo Puyo games, the player does not receive the puzzles in a linear fashion. Instead, the player is presented with a hub world where they take control of Arle Nadja and receive challenges from other characters. Each character has a number of puzzles that are unique to them, which are presented to the player in a random fashion. When enough of a character's puzzles have been cleared, the player is declared victorious.

The core gameplay is similar to previous Nazo Puyo games: each puzzle consists of a preset board, a victory condition, and a set of Puyo that will be made available to the player. A new addition to Arle no Roux is a health system. Whereas previous Nazo Puyo games will endlessly provide irrelevant pairs to the player once they have use up their "allotted" Puyo, Arle no Roux will immediately fail the player. Failing a puzzle will reduce Arle's health, which is depicted via her facial expression as a nod to the Madou Monogatari series. Arle will become increasingly depressed as the player fails, and losing when Arle's portrait depicts her gritting her teeth will result in a Game Over. Arle's health is completely restored when a player earns a Level Up, as well as when the player clears enough puzzles to defeat the challenger.