Historia Crux

The Historia Crux (ヒストリクロス) is a gameplay and story element from Final Fantasy XIII-2. It allows players to travel between locations and visit them in different time periods. To unlock new places and time periods, the player needs to find artefacts located all over the world. Visiting these areas at different times will give players access to new items, and it can also change the course of the game.

It is revealed that there will be opportunities to see characters at different ages, replay the game, and see multiple endings by utilizing this system. This will allow a fully powered team to fight any previous bosses from the game with much more of an advantage. Though the future can be visited, the events before or during Final Fantasy XIII cannot be revisited as this would cause a time paradox to ensue.

The date system is marked by the letters "AF", which stand for "After the Fall". Currently known visitable years are: 3, 5, 10, 100, 110, 200, 300, 400, 500, and 700. In each location and time, there are a certain number of "Fragments", with 160 in total. For example, there are 5 Fragments to be found in the Yaschas Massif -010 AF-. 1X AF or 4XX AF signify that the node contains 10 AF and 400 AF with paradoxes resolved respectively. There are also places marked with year unknown such as "Serendipity -Year Unknown-" and displayed as "??? AF" when travelling to them.

Datalog
''The Historia Crux is the crossroads between the Time Gates. It is a separate dimension connecting one age to the next.''

''This surreal plane is said to be the border of the chaotic realm of Valhalla, and only those with an affinity for the power of chaos are able to use it to travel through time. Even the godlike fal'Cie are not free to enter the Historia Crux as they please.''

Story
In the aftermath of the events that took place in Final Fantasy XIII, Lightning is captured by darkness from another world and dragged to the edge of time, thus written out of history. She falls through the Historia Crux, and is transported to Valhalla.

Three years later, Serah Farron travels with a mysterious young man named Noel Kreiss on a quest to rescue Lightning, and together they visit various time periods through the Historia Crux. When Serah asks Noel how he came to exist in her own time period, he reveals that it was because of the Historia Crux itself, and he explains to her what it is.

After leaving Academia -4XX AF- through a time gate, part of the Historia Crux is damaged and hits Mog causing him to be thrown out of the system. Serah rushes to help him and after saving Mog, she is separated from Noel where they leave through different exits but end up in the Void Beyond.

Academia

 * 400 AF, a paradox Academia full of Cie'th, due to the intervention of Adam
 * 4XX AF, the true Academia 400 AF, in a timeline where Adam was never created.
 * 500 AF
 * XXX AF, Transcript: The Future is Hope ending.

Archylte Steppe

 * ??? AF, Archylte Steppe during the period 1 AF - 500 AF
 * XXX AF, Transcript: A Giant Mistake ending.

Augusta Tower

 * 200 AF
 * 300 AF
 * ??? AF, Transcript: Test Subjects ending.

The Void Beyond

 * ??? AF, a shadow of Valhalla.
 * ??? AF, a dream world in New Bodhum known as Hollow Seclusion. Also home to the Transcript: Fate and Freedom ending.

Bresha Ruins

 * 005 AF
 * 100 AF
 * 300 AF

Coliseum

 * ??? AF
 * XXX AF (DLC)

A Dying World

 * 700 AF
 * XXX AF, Transcript: Heir to Chaos ending.

New Bodhum

 * 003 AF
 * 700 AF
 * XXX AF, Transcript: Beneath a Timeless Sky ending.

Oerba

 * 200 AF
 * 300 AF
 * 400 AF
 * ??? AF, Transcript: Vanille's Truth ending.

Serendipity

 * ??? AF
 * XXX AF (DLC)

Sunleth Waterscape

 * 300 AF
 * 400 AF
 * XXX AF, Transcript: Mog's Marvelous Flan Plan ending.

Valhalla

 * ??? AF
 * Locked location (as of 29 February 2011)

Vile Peaks

 * 010 AF
 * 200 AF

Yaschas Massif

 * 010 AF, a paradox Yaschas Massif, darkened by an eclipse caused by the fal'Cie Fenrir.
 * 01X AF, the true Yaschas Massif, in a timeline where the eclipse never happened.
 * 100 AF
 * 110 AF

Music
The Historia Crux has its eponymous leitmotif, titled "Historia Crux", composed by Mitsuto Suzuki and performed by ORIGA.

Lyrics

 * The stars shine in the deep sky
 * Endless stories of the distant yesterdays


 * Take me in your arms
 * Keep me in your heart
 * Take me in your arms
 * Keep me in your heart


 * Time is flying by
 * The only moment is now, the only moment is now
 * Feel that everything is real
 * Everything is real in the dream


 * Going on a trip to somewhere I've never been
 * Across time and space
 * Time and space, time and space
 * Time and space, time and space


 * The stars shine in the deep sky
 * Endless stories of the distant yesterdays

Etymology
Historia is Latin for "history", whilst Latin crux means "to intercept at a central point" - in other words, "to cross".