Invasion

Invasion (called Infiltration on the Revival disc) is Disc 1, Track 18 on the Xenogears Original Soundtrack and track 19 on the Xenogears Original Soundtrack Revival Disc -the first and the last-. It is one of the tracks playable in the Nortune jukebox, under the options 'The World' and 'Emotion'.

It plays as the area music in the following areas: It also plays in the following cutscenes:
 * Nortune (except for the Battling Champ's room and Kaiser Sigmund's rooms)
 * The Bledavik waterway
 * Fatima Castle before the party reaches Nisan
 * The land-dwellers' quarters areas in Solaris
 * Krelian's lab until the room with Opiomorph
 * In Solaris after Citan removes the party's limiters
 * The first Anima Relic dungeon (until the party reaches the bottom floor)
 * Bart and his crew prepare to capture Shakhan after entering Fatima Castle through the waterway.
 * Fei meets in Nortune.
 * Fei and Rico temporarily part ways after leaving the D-Block sewers.
 * Hammer lets the party know about the Goliath.
 * The party looks over Nisan, which is currently overtaken by Shakhan's soldiers.