Here is an overview of the game, via Bigben Interactive:
Taking place in the 1920s, The Sinking City is a game of adventure and investigation set in an open world inspired by the works of the famous American horror author H.P. Lovecraft. Players step into the shoes of a private investigator who arrives in the city of Oakmont, Massachusetts — a city suffering from unprecedented floods of supernatural phenomena. Players must uncover the source of whatever has taken possession of the city, and the minds of its inhabitants.
Watch the 13-minute E3 2018 gameplay trailer below.