The action RPG features characters from both anime series, and you can mix and match them in your party.
Sword Art Online and Accel World were written by the same author, Reki Kawahara, and both center around popular fictional MMOs. Accel World games have only been released in Japan thus far, while Sword Art Online has had several game adaptations that came West, most recently Sword Art Online: Hollow Realization on PS4 and Vita.
Accel World vs. Sword Art Online was previously announced for Japan and will launch there on March 16.