Music of Xenoblade Chronicles X

The music of Xenoblade Chronicles X consists of 55 officially released music tracks totalling roughly 83 individual pieces of music. All of the music was composed and arranged by Hiroyuki Sawano. mpi wrote lyrics for the numerous vocal themes, which were sung by mpi, Mika Kobayashi, Cyua, David Whitaker, Aimee Blackschleger, and Sayulee. Yumiko Inoue and Sawano himself also provided vocals for various tracks.

In official releases of the music, Sawano chose to organise it in a manner that is typical for his own music but uncommon for the Xeno series as a whole, in that clearly distinct pieces of music would be included as part of the same track. For example, no7=G-LOW-S→F.S.K.O from 0:00 until 3:36 is substantially different from the track from 3:36 until 5:28, both musically (for example, the intensity and melodies used between the two parts are different) and functionally (the two parts of the track never play together in-game, and another track is a remix of the first part but not the second).

For clarity, in the following, 'track' will always be used to refer to an entire track, whereas 'piece (of music)' will be used to refer to the separate parts within a track where applicable. When necessary, different pieces of music within the same track may be distinguished by the (unofficial) suffix " (part 1)", " (part 2)", etc. For example, no7=G-LOW-S→F.S.K.O (part 1) is a piece within the track no7=G-LOW-S→F.S.K.O. Details on how the tracks are split into pieces are included in each track's individual wiki page.

Functionality in-game
Slightly under half the pieces of music used in Xenoblade Chronicles X were used in cutscenes ('cutscene themes'), about a fifth were used as background music during battle ('battle themes'), and about a quarter were used as background music during regular gameplay when in the overworld outside of battle ('area themes'). 4 pieces of music play specifically while in menus. There are also 5 pieces which were included as part of official soundtrack releases (see below) but never play in-game. There is some overlap with regards to pieces of music serving different functions: if there is a cutscene immediately preceding a battle, the battle music may start playing during the cutscene. Moreover, the menu themes often independently serve as cutscene themes.

In many areas, there are separate pieces of music that play during the day and the night. When this happens, the music that plays during the night is often (but not always) a remix of the music that plays during the day, and is almost always more subdued than the day theme — the main exception is the music of Sylvalum, 46-:ri9, whose night theme is more energetic than its day theme.

Many tracks with multiple pieces (often called "double tracks", "triple tracks", etc.) combine pieces that have similar functions in some way — for example, when an area has both day music and night music (see above), there will be one track that contains both pieces. However, this is not universally true; many tracks contain multiple pieces used in unrelated situations (e.g. aBOreSSs, whose two parts function as the battle music for unrelated bosses), and some even contain multiple pieces with completely different functions (e.g. no10=CR17S19S8, whose third part functions as battle music whereas its first two parts function as cutscene music).

Priority
In Xenoblade Chronicles X, it is possible to be in situations where the conditions for multiple pieces of music to play are being met at once. This often happens in battle, when multiple enemies which use different battle music are engaged at once. The game uses a priority system to determine which music should play; the following is a general ordering of which battle music tends to take priority, arranged from highest to lowest:
 * Wir fliegen
 * Story boss themes (e.g. no3=NO.EX01)
 * Uncontrollable
 * z37b20a13t01t08le (part 1)
 * Other battle themes

The game also uses the following priority rankings (high priority to low priority) to determine which area theme should play when multiple conditions are met (in particular, when the player character may be using a Skell's Flight Module):
 * z15f20i12e09l14d (part 2), z?2f0i1e2l0d914, z12e201v2e091n4t (part 1) and (part 2)
 * Don't worry
 * All other area themes (N周L辺A (part 1) and (part 2), X-BT1, etc.)

Musical style
The music as a whole contains many of the earmarks of Sawano's style: a very heavy emphasis on percussion, thick textures, and melody lines that continue having notes right up until the ends of musical phrases all feature prominently. The music does contain tracks that have substantial departures from this style, however; NEMOUSU秘OUS (part 1) is almost entirely in a choral style, and three tracks are solo-piano arrangements of other tracks (PianoX1, PianoX2, and PianoX3). A relatively high proportion of tracks contain intelligible vocals, mostly sung in either English or German; however, these are not always the focus in the tracks in which they appear, and only a fraction of these have official lyrics.

Track titles
The titles of the Xenoblade Chronicles X tracks are somewhat infamous in their complexity and unpronounceability; only a handful of the tracks are in intelligible English. Many contain what look at first glance like jumbled collections of lowercase and uppercase letters. A significant number of the track titles start with 'z' and contain digits and letters mixed together — several of these names are nigh-identical, such as z12e201v2e091n4t and z13e20v12e09n14t. Even odder, some tracks contain punctuation or even kana and/or kanji interspersed in titles that otherwise use Latin characters.

However, most if not all of the names do have meaning. The more complicated track titles are typically 'encoded' forms of actual words. For example, no4=D91M decodes to 'track number 4: Requiem'. The extent to which this is obvious varies; some tracks (e.g. aBOreSSs) are simple to interpret ('Ares Boss'), whereas others (e.g. no8=UN↑口and巨DIE, decrypting to 'track number 8: michi kyodai', i.e. 'huge and unknown') took several years for fans of the music to decode. It is assumed that all of the tracks either have obvious meaning or some encoded meaning, although not all of the encoded meanings are known; for example, the significance of the 'F.S.K.O' in no7=G-LOW-S→F.S.K.O is unknown. Where encrypted meaning is known, it is included on the individual track pages.

The decoding process is helped substantially by the fact that the titles on the JASRAC database are different from how they appear on the XenobladeX Original Soundtrack — often, they include the titles directly decoded into plain Japanese kana, whereas in other cases they provide hints as to how the titles are intended to be pronounced out loud.

While this confusing nature of the titles is standard for the music of Hiroyuki Sawano (much like the nature of multiple pieces being included in one track), it stands out strongly among the rest of the Xeno series' soundtracks, leading to the track titles' infamy among fans. To avoid confusion among people unfamiliar with the titles (e.g. due to people having played the game but not looked into official releases of the music), much of the music is often referred to by its function (especially area themes). For example, rather than using the name N市L街A or 'NLA Shigai' (the JASRAC version of the title), fans will often simply refer to the parts of the track as 'NLA day'/'NLA night'.

Not all of the tracks have very confusing titles; several are in plain English (e.g. Black tar and The key we've lost) and some are in German (e.g. So nah, so fern). These more intelligible tracks tend to also be those with lyrics as a strong focus. Curiously, all of these only have the first word in the track title capitalised except for Your Voice, which has both words capitalised.

XenobladeX Original Soundtrack
The XenobladeX Original Soundtrack is the most complete official release of the music of Xenoblade Chronicles X, containing almost all of the music used in-game as well as several unused tracks. It consists of 55 tracks split across four discs. The soundtrack was released on the 20th of May, 2015, only in Japan.

The organisation of the soundtrack is relatively unorthodox. The first disc and the second disc mostly consist of cutscene themes and battle themes whereas the third disc mostly consists of area themes; however, there are some area themes included in the second disc and some battle themes and cutscene themes included in the third disc. The 4th disc contains 'bonus tracks', most but not all of which are rearrangements of other tracks elsewhere on the soundtrack, and some but not all of which went unused in-game. While there is some slight correlation between area themes that are placed earlier in disc 3 and areas that a player is likely to go to earlier in-game, there are outliers (e.g. the NLA themes coming after the Noctilum themes), and there is no such correlation for the cutscene, battle or menu themes.

Included alongside the soundtrack was a booklet containing official lyrics for the tracks Your Voice, Wir fliegen, So nah, so fern, Black tar, Uncontrollable, By my side, In the forest, The way, The key we've lost, and Don't worry.

In the booklet's track listing, the first 11 tracks on Disc 1 are separated from the rest with the header 0rCH-SUITE "X". (These tracks all have a prefix of the form 'no1=', 'no2=', etc. before the rest of the track title.) It is assumed that this is supposed to indicate that they form a suite of 11 tracks, although this suite has not been released independently.

Xenoblade Chronicles X Soundtrack Selection
The Xenoblade Chronicles X Soundtrack Selection is a disc containing 10 tracks from the music of Xenoblade Chronicles X, released as part of the Xenoblade Chronicles X Special Edition in North America on the 4th of December 2015. Notably, the track listing contains titles that differ from both those of the XenobladeX Original Soundtrack and its JASRAC listing — in particular, the 'no=' prefix on tracks from 0rCH-SUITE "X" was removed, and the kanji in N周L辺A and N木ig木ht木L were replaced with English representations of their meaning (although still interspersed throughout the titles as the kanji were).

Track List

 * 1) CODENAMEZ
 * 2) THEMEX
 * 3) MONOX
 * 4) Wir fliegen
 * 5) z5m20i12r04a28
 * 6) Uncontrollable
 * 7) In the forest
 * 8) aNrLeAa
 * 9) NOfCoTreIsLtUM
 * 10) Don't worry

Unreleased music
The music files in-game contain many variations on tracks included in the XenobladeX Original Soundtrack. For the most part, these variations are simply the same tracks but looped differently or with different starting and stopping points. However, there are also several versions of music tracks that are substantially different from the versions in the OST:
 * A version of z15f20i12e09l14d (part 1) with only vocals, which plays in the Lifehold Core.
 * A non-vocal version of Uncontrollable, which plays during Time Attack Mission battles.
 * A different take of PianoX2 with substantially different structure and ornamentation, which was used in several cutscenes.
 * A different take of PianoX3 (which, like the OST version, was unused in-game).

In other media

 * Uncontrollable and Wir fliegen are playable in Xenoblade Chronicles 2 under certain circumstances.
 * Melancholia was originally released as Melancholia ~featuring vocal: Aimee Blackschleger~ as Track 11 on Hiroyuki Sawano's musica album, released on the 15th of July 2009, before Xenoblade Chronicles X began development. (The version that appears in Xenoblade Chronicles X is a remix of the original.)
 * Don't worry and Uncontrollable were performed at SawanoHiroyuki[nZk]004, a live performance of Sawano's works, and included as Disc 2, Track 7 and Track 9 respectively on the associated album 2V-ALK / SawanoHiroyuki[nZk] [Limited Edition] which was released on the 20th of September 2017.
 * So nah, so fern (Mika Type Version), a remix of So nah, so fern, was included as Disc 2, Track 6 on Mika Type I / Mika Kobayashi, a collection of Mika Kobayashi's vocal tracks released on the 22nd of June 2016. This track as well as Your Voice were included as Disc 2, Track 6 and Track 9 respectively on Mika Type Ro / Mika Kobayashi, another collection of her vocal tracks released on the 10th of January 2018.