Yes, in some interview he mentioned that Qud at the time was running as if it were a console app inside Unity. I don't know if that is still true after their UI overhaul, but if so it always seemed odd not to port it to MonoGame instead and save paying the fees.
Scanlines and vignette are simple to implement and the main stylistic shaders they use. They also use a grayscale one if you trigger a specific situation. There might be others, but again, simple to write.
They also use the particles system for candelabras. Could be reproduced in many engines.
