During the game, Aoto, the protagonist, can dive into the 'Cosmospheres' of certain Reyvateils to craft Song Magic, which is done by witnessing their internal turmoils and traumas and helping them to find a solution for them.
[3] However, unlike the previous games, the player can only gain Hyumas in the Cosmosphere because the Song Magic used by each Reyvateil and their persona is preset and unmodifiable.
Additionally, the player can make the Reyvateil Purge (shed off part of her clothes) in order to increase the power of her Song Magic.
If they did it correctly, the Reyvateil will Purge part of her clothes, the Burst Gauge will increase its charge speed, the Song Magic will level up to its next stage, and the party will gain an additional elemental attack and resistance depending on which button they held for executing the Purge (L1: Fire, L2: Wind, R1: Ice, R2: Lightning).
At the Reyvateil's fourth-level Purge, she will unleash her Song Magic Flipsphere, requiring the player to attack in sync with the pulsing of the Harmograph line.
The entire region is under the dominion of the Reyvateil-ruled country of Clustania, located in the upper zones of the Tower, and its army periodically goes to the Great Fang to destroy the towns that have grown to much and to take its inhabitants as prisoners.
However, the villages see constant destruction as described above, while the Eternus Shaft is out of their reach due to its underground location, and Ciela Gate is under the protection of the Archia Corporachy.
The players will take on the role of a young steeplejack apprentice called Aoto, who upon getting awakened by a ruckus outside his house, goes to investigate to find out that Clustanian soldiers are attacking an old man and girl that looks like a swordswoman.
Aoto tries to head to the airbus terminal in order to run away from his village with Saki before the Clustanians catch them, where he meets a friend of his called Tatsumi.
After they get away from the village, Saki wakes up, unable to remember anything about Kiraha or the events that just took place, so Tatsumi advises Aoto taking her to a Reyvateil doctor he knows at Eternus Shaft.
Aoto (蒼都)[3] Saki (咲)[3] Finnel (フィンネル, Finneru)[3] Hikari Gojō (光五条) Tatsumi (タツミ) Gengai (ゲンガイ) Raphael (ラファエーレ, Rafaēre) Richaryosha (リッカリョーシャ, Rikkaryōsha) Akane (アカネ) Kukurou (ククロウ) Teppo (テポ, Tepo) The soundtrack for the game was composed by the Gust Sound Team, though its configuration changed in comparison to the previous games: only Ken Nakagawa remained, as Akira Tsuchiya was busy being the director and main creator of all the aspects of the game, while Daisuke Achiwa was at the time working solo in the score for Atelier Lina.
For the Hymns, three of the singers employed so far in the series made a return: Akiko Shikata, Haruka Shimotsuki and Noriko Mitose, alongside which several new singers joined the team for the game: Kokia, Yoko Ueno, Au (from the Gusya Ningen band), Azumi Inoue, Noriko Fujimoto, Yula Yayoi, Rekka Katakiri and Haruka Togawa.
[5] Similarly to its predecessors, it received a large amount of related merchandise in the form of music CDs, as well as gag manga compilations, Drama CDs that told events that took place after the game's true ending, a Hymmnos Musical chronicling happenings between the events of Ar tonelico II: Melody of Metafalica, a player's guide, a setting materials book, and two novels that also served as an epilogue to the entire series.
[citation needed] The gameplay is its most criticized aspect due to not being an evolution of the battle system used in Ar tonelico II, and instead being what players have come to call a "half-baked attempt at a real-time combat system", between the few attacks the players can use, the absence of multiple kinds of Song Magic and the lack of variety in enemy models.
[citation needed] Its localization hasn't been as severely criticized as Ar tonelico 2's due to the script being more polished in general, although it still has some flaws, such as translating some terms inconsistently, the translators and editors not following their word of correcting all the Hymmnos terms mistakes they had committed previously, and finally, a bug that causes the final level of a Cosmosphere to have desynchronization between the voiceovers and the written text due to having introduced an additional text box when playing through that section with the Japanese voices on.