What did David Fincher and Zach Creggar do on Unhinged, exactly?

The new Netflix interactive streaming horror game Unhinged has just been released on the platform and there’s a big mystery at the core of it: Filmmakers David Fincher and Zach Creggar are both involved… they get a special thanks in the credits… but it is unknown exactly what they did.

This Variety article suggests their involvement was substantial.

Befo…