An anime adaptation of the six volume novel series Sword Art Online: Progressive by Reki Kawahara has been announced, following the completion of Sword Art Online: Alicization - War of Underworld 2nd Season. 

Sword Art Online: Progressive Anime Teaser Visual

The official website for Sword Art Online released the above visual (above) as well as an announcement video (Japan only). No information regarding the time of release has been provided at time of writing.

Here's the version of the video that was shared on the official Twitter account:

Sword Art Online Progressive 1 Volume Cover (via Yen Press)

The Sword Art Online: Progressive novel series is a retelling of the events of the Aincard arc of Sword Art Online, started nearly a decade after author Reki Kawahara wrote the original web novel. Yen Press describes the first volume of the series as follows:

'There's no way to beat this game. The only difference is when and where you die...'One month has passed since Akihiko Kayaba's deadly game began, and the body count continues to rise. Two thousand players are already dead. Kirito and Asuna are two very different people, but they both desire to fight alone. Nonetheless, they find themselves drawn together to face challenges from both within and without. Given that the entire virtual world they now live in has been created as a deathtrap, the surviving players of Sword Art Online are starting to get desperate, and desperation makes them dangerous to loners like Kirito and Asuna. As it becomes clear that solitude equals suicide, will the two be able to overcome their differences to find the strength to believe in each other, and in so doing survive?Sword Art Online: Progressive is a new version of the Sword Art Online tale that starts at the beginning of Kirito and Asuna's epic adventure--on the very first level of the deadly world of Aincrad!