I spent my holiday break bingeplaying the Submachine series and giving ink painting a try. My skills and free time are sub-optimal for actually making an escape-the-room game of my own but I can sure as hell draw the environment.
There actually is a solution here. Some of it is on the other side of the room, which will be uploaded later.
Dr. Ph. Martin's Bombay inks and white gel pen, Canson XL watercolor paper, assorted cheap watercolor brushes and dip pens.