2D sidescroller action brawler.
Being discussed right now at SE Presents E3 Day 1.
Edit: For PS4/XBONE, out 9.30.16
Trailer to debut at Comic-Con
Edit 2: It's exclusively a GameStop pre-order bonus in the US.
The game is set 30 years before FFXV and you play as King Regis (story is told from the perspective of a fairy tale being told to Noctis).
Edit 3: Official website.