Here is what they had to say about it:
Ubisoft released the first video in a series of Developer Diaries for Valiant Hearts: The Great War. Presented by Art Director Paul Tumelaire, the following video focuses on “Art & Emotion” in the game and details how the team developed the unique art style and concept used to tackle the emotional story of everyday citizens during the First World War.
Valiant Hearts: The Great War will be available a digital download for Xbox One, Xbox 360, PS4, PS3 and PC on June 25th.
And here is the video:
Article by Nick