Darkside, that was the codename given to a new IP developed by Sony Santa Monica for PS4. This new project tried to merge several mechanics… and maybe Darkside died because of its ambitions.
The game was supposed to be an action game that combined RPG mechanics, customization, vehicles and more. All of it set in a post apocalyptic open world. Unfortunately, the game did not achieve to get a working action-melee combat with guns. This was one of its critical issues.
Many concept art from the early stages of the game have recently surfaced. The media comes from Erik San Juan, a former Game Developer & 3D Concept Designer, who worked at Sony Santa Monica during many years. He was involved in games such as Kinetica, God of War, God of War II, God of War III, God of War Collection, God of War Saga and God of War Ascension.
As far as we can see in the art, Darkside was a futuristic game (maybe with worlds exploration) with mercenaries, drones, kraken-like creatures, skeletal monsters with long arms and some kind of scanning system that collects new information about creatures.
Concept art gallery by AllGamesDelta.