There's plenty we don't know about what goes on within the game industry, but it's pretty obvious to suggest there are plenty of projects being worked on right now we have no idea exists. Colin Moriarty, forging his own path post-Kinda Funny, no doubt has plenty of connections, so he's probably more in the know than most.
In a response to a fan question on Twitter, Moriarty let out an aside that suggests there's a "fairly substantial PS4 exclusive yet to be announced from second party."
Second party in this case refers to a studio independent of Sony producing a game exclusively for PlayStation 4. Insomniac Games is probably the most famous example of this in light of Marvel's Spider-Man and many other titles, but other examples include Quantic Dream's Detroit: Become Human and Supermassive Games' Until Dawn. It's an arrangement Sony's utilised many times throughout PlayStation's history, and it's likely most of Worldwide Studios is working on PS5 games, so an unannounced exclusive from a second party makes sense.
The only title we can think of that this may refer to is Bluepoint's long-rumoured remake of Demon's Souls, but realistically, this could be almost anything. What do you think Colin Moriarty could be talking about here? Does he know something, or is this a whole lot of nothing? Speculate away in the comments below.