Released in 2008, ''Sigma Harmonics'' is a Creator/SquareEnix RPG for the UsefulNotes/NintendoDS, developed by the team that had previously worked on ''VideoGame/DirgeOfCerberus''. It is set in an alternate Tokyo, and focuses on the story of Sigma Kurogami, the future head of the Kurogami clan, a line of 'sound-users' who can create miracles and guard the Great Clock that seals the demonic Ouma. The story begins when someone changes the past, destroying the present day and releasing the Ouma.

To put things right, Sigma and his friend, the card-user Neon Tsukiyumi, travel back into the past in order to solve a series of murders in the Kurogami household. By visiting different points in time, finding clues (in the form of 'moments of sound'), and working out the sequence of events and the culprit, the past can be changed, leading to a different murder scenario. In battles with the Ouma, Neon does most of the fighting, using her cards to perform actions whilst Sigma provides the BGM. By playing different tracks, the individual recharge rate for Neon's cards is changed. Neon can also change forms via a form of possession.

This game has an [[CrowningMusicOfAwesome excellent soundtrack]], composed by Creator/MasashiHamauzu, and beautiful anime-style artwork. Sadly however, it has not yet been released outside of Japan.

!!Tropes associated with this game include:

* AltumVidetur: The theme song is named "Harmonia vita" and has some Latin sprinkled throughout the lyrics.
* BlackEyesOfCrazy: [[spoiler:Rin during the final battle, coupled with RedEyesTakeWarning.]]
* CoolMask: Worn by the butler.
* CrowningMusicOfAwesome: [[ Hope Given Dance of the Dog's Howl ]]
* DoItYourselfThemeTune: Creator/AyaHirano sings the theme song, "Harmonia vita".
* EvidenceScavengerHunt: After going back to a certain time and a certain place, Sigma can use his sound-related powers to uncover 'moments of sound' - clues as to what happened in that place during that time.
* FightLikeACardPlayer
* FlamingHair: Dickson and Christie.
* GreenEyes: Sigma
* HumongousMecha: [[spoiler: Used in the final battle.]]
* ImpaledWithExtremePrejudice: [[spoiler: Neon]], at the end of the trailer.
* NiceHat: Neon.
* NoExportForYou: Bombed in Japan, which sealed its fate in regards to an international release. It doesn't help matters that the game is coded in a way that would make hacking in a fan-made English script impossible.
* OneWingedAngel: [[spoiler: Rin]] in the final boss battle, this is a Creator/SquareEnix game so it shouldn't really come as a surprise.
* PowersViaPossession: Neon uses this to change classes. It also comes with a slight personality shift.
* RippleEffectProofMemory
* SayMyName: At the end of the trailer when Neon gets skewered.
* SetRightWhatOnceWentWrong: Sigma and Neon's goal.
* TheSummation: After gathering evidence, Sigma can do this via Hyper-Inference (a board with the 'moments' placed on it in the form of medals, which can be placed in different ways, producing different reasonings). Whether he infers rightly or wrongly affects the boss battle afterwards.
* TimeTravel
* ThemeMusicPowerUp: What piece of music Sigma is playing affects the recharging rate for Neon's cards. [[spoiler: Rin produces the opposite effect in the final battle by changing the track.]]
* TrustPassword: Sigma uses one to get past the butler after he has forgotten him due to the changes in the timeline.