Well that was Six Flags who did Suicide Squad and the timing made sense. When the game was fresh and new, The Dark Knight was still (and kinda still is) in the social conscious and people would've been expecting a Nolan-esque environment, so it makes sense to wait a bit, especially now that the new DCEU flopped.
From the artwork they're showing on the website, it's specifically the video game. I'm sure they'll take all sorts of creative liberties, but I'm sure the video game will
be used as the visual aesthetic.