The official Twitter account for Sword Art Online announced that the Sword Art Online: Progressive light novel series will receive an anime adaptation.
Reki Kawahara, the author of the light novel series, published the Progressive parallel series back in 2012. The story retells the Aincrad Arc from Sword Art Online.
Details about the anime adaptation have yet to be announced.
《アリシゼーション》編の最終話放送直後に公開となった「ソードアート・オンライン プログレッシブ」アニメプロジェクト告知映像はこちら!
— アニメ ソードアート・オンライン 公式 (@sao_anime) September 19, 2020
YouTube:https://t.co/Ci62vkSWRE
公式サイト:https://t.co/rivYvY6aHD#sao_anime pic.twitter.com/kMT4SPxio1

Yen Press is publishing the English version of the series and describes the first volume as:
“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?
Source: Sword Art Online Twitter