How did Final Fantasy music get its own concert tours?

Nobuo Uematsu, a self taught musician who joined Square in 1986, composed the scores that defined the series from its 1987 start. The music did not stay inside the cartridges. Soundtrack albums came first, and arranged albums followed, among them the Piano Collections line, which recast battle and town themes as solo piano pieces fans could buy, study, and play.

The concert record starts earlier than most players guess. A Final Fantasy Symphonic Suite was performed on May 20, 1989, for a limited audience, to create orchestral versions of the first two games' music. The full public breakthrough came on February 20, 2002, when the concert titled 20020220: Music from Final Fantasy filled the Tokyo International Forum: the Tokyo Philharmonic Orchestra, conducted by Taizo Takemoto, played seventeen pieces spanning the first game through Final Fantasy X, to a sold out crowd, with the voice actors of Tidus and Yuna hosting.

After that the tours stacked up. Tour de Japon took the concerts to seven dates in six Japanese cities in the spring of 2004. Dear Friends: Music from Final Fantasy toured the United States from 2004 to 2005, the first North American tour devoted to the series, opening with the Los Angeles Philharmonic. In parallel, Uematsu formed The Black Mages in 2002 with fellow composers Kenichiro Fukui and Tsuyoshi Sekito, a six piece rock band that arranged his battle themes across three studio albums, in 2003, 2004, and 2008, before disbanding in 2010; he kept playing the arrangements with a successor band, the Earthbound Papas.

The lasting institution is Distant Worlds: Music from Final Fantasy, which opened in Stockholm on December 4, 2007, with Arnie Roth conducting, and has toured the world ever since, Uematsu working closely with Roth on the repertoire and a shelf of live albums documenting it. His themes have also entered Britain's Classic FM Hall of Fame listings, a fan voted classical chart. The short answer to the question is demand, documented at every step: each format sold, so a bigger one followed.