Pick an art movement that dates from before the 1950s (eg Prehistoric art or ) and design a game idea that would be work with graphics in this style. Try to design gameplay that matches the aesthetics of the art style.
I go with Romanticism, which the art movement during industrial revoluation.
Look at the artwork on that time ( from http://en.wikipedia.org/wiki/Romanticism).. it looks very emotional, and elegance. So I would like to have a stroy/novel/rpg game, with this kind of artwork..
Since this kind of artwork, from what i could imagine would not be good for animation, I would use this kind of artwork for the background and environment, but not for the people.
Since I guess this kind of artwork would fit with many history them, I’ll go with france history about Napoleon Bonaparte.. So this would be the story about you as a napolen boneparte. since It would be an rpg game, you can control the napoleon, make decission on how do you want to do the war, how could you win the war, the strategy, also making a decission as a king and so on. as all the rpg games. it would be heavily involve the artwork and video.