Hey Matt, thanks for playing and leaving a comment. Your game looks cool! Going analog for your sets instead of purely digital seems like a daunting task, but I've seen other examples of people doing this with success.
As for my process, a lot of my inspirations for this game were examples of using only what is essential. For example, in the game "Limbo" there isn't any color most of the art is just light and shadow and a focus on silouettes. For my previous game, "The Search" I went crazy with detail everywhere and while it was fun and I felt it turned out well artistically, I felt it made me lose focus on the gameplay and puzzles. This kind of detail is fine if you're a AAA studio with a lot of time and cash but I'm just a solo dev so I have to be more focused in my efforts. Traditional artists like John Register and Edward Hopper were inspirations for the art style of Discolored. Especially if you look at Register's work, again mostly light and shadow doing the work, simple shapes and use of color. There are other games that do this as well like The Witness. I could go on and maybe I'll write a blog post about it later. :)
As for my tools, I kept everything digital. Using Unity for the engine, 3ds Max for modeling and lighting with Vray to render out lightmaps because I don't like Unity's current lighting system. Also using a few plugins in Unity for functionality like Playmaker, Rewired, and Adventure Creator.
Anyway, hope that was helpful and best of luck with your game!