Looking for styles of art that use a flat-shading style, I found that older (circa 1920-30) travel posters can be particularly successful at evoking beauty and a strong sense of place. The lack of shading brings emphasis to the careful choice of shape and colour as well as to the composition of the poster.
The London, Midland & Scottish Railway commissioned a lot of beautiful posters from artists such as S.R. Wyatt and Norman Wilkinson.
My previous post discusses one of the reasons I’m looking at more minimal visual styles.
Moving into explorable, three dimensional spaces, I used toon shaded materials in Unity with cel-shading ramps. These ramps allowed me to create dynamic lighting with blocks of colour and to have more control over the exact colours of the lit and un-lit areas on each object.
Somewhat like Impressionism, travel posters often use unexpected colours (e.g.: purple for shaded areas) or somewhat ambiguous shapes that rely on each other in order to make sense.