A science fantasy game with cooperative multiplayer elements, it takes place in far-future New York City, and players are teleported back in time by touching magical artifacts.

[1][2] The historical sections of the game take place in a medieval/fantasy setting in procedurally generated dungeons, with the player equipped with suits of armor, swords, pikes, shields etc.

This 'Raven' is brought into contact with excavated objects from a mysterious civilization in Bohemia (Czech Republic) dating from the 15th century and are asked to use their abilities to explore the city and discover its secrets.

[7] In early 2015, Kazunori Sugiura stated in an interview with 4gamer that the vision for the game had expanded since its initial 2013 reveal, to better appeal in the long term to players, and so the development timescale had been extended.

[12] In September 2021, former chairman of SIE Worldwide Studios Shawn Layden stated that he had "no idea" what happened to Deep Down but says that other team members of Yoshinori Ono might pick up the game further to develop.