Short answers, pulled from the story.
Final Fantasy XII: Revenant Wings is a real-time strategy game for the Nintendo DS, co-developed by Square Enix and Think & Feel. It is a standalone sequel to Final Fantasy XII and the first entry in the Ivalice Alliance, a collection of games set in the Ivalice universe.
Revenant Wings was released in Japan on the 26th of April 2007, in North America on the 20th of November 2007, in Australia on the 14th of February 2008, and in Europe on the 15th of February 2008.
As of August 2008, Revenant Wings had sold 1.04 million copies worldwide: 540,000 in Japan, 220,000 in North America, and 280,000 in Europe. It topped Japan's sales charts in its first week of release.
Motomu Toriyama directed and co-wrote Revenant Wings, with Takanari Ishiyama serving as co-director and co-writer. Akitoshi Kawazu was executive producer, and the game was co-developed with Japanese studio Think & Feel.
Producer Eisuke Yokoyama drew the combat design from Warcraft and Age of Empires, which he had played as a student. The team also studied Final Fantasy XII and popular Nintendo DS titles to understand what made each resonate with players.
Kenichiro Fukui composed the original score, supervised by Hitoshi Sakimoto. Most of the music consists of arrangements of Sakimoto's Final Fantasy XII soundtrack, with additional contributions from Mitsuhiro Kaneda, Kimihiro Abe, and Noriyuki Kamikura.