The final episode of the anime Sword Art Online: Alicization – War of Underworld aired, along with the announcement that the light novel Sword Art Online: Progressive will be adapted into an anime.
The Sword Art Online: Progressive novel was therefore released in 2012.
Also written by Reki Kawahara , the novel is a new version that tells the story of Kirito and Asuna still in Aincrad.
Source: ANN