The 2017 release is planned for PlayStation 4 and Vita
Sword Art Online, a gaming sci-fi by Reki Kawahara set in the year 2022, and Accel World, a gaming sci-fi set in the year 2046, have met in 2011 prose story "Versus," adapted into a track on the 2012 Accel World + Sword Art Online Drama CD, and a manga included in volume 5 of Accel World's. Also, AW lead Black Lotus (Kuroyukihime) made an appearance in the game Sword Art Online: Lost Song.
Now, announced at this weekend's Dengeki fall event, they're meeting again in game Accel World VS Sword Art Online: Millennium Twilight. The 2017 release is planned for PlayStation 4 and Vita.