The Yume Nikki mod for Lonely Inky. Unfinished.
This is the only preserved gameplay video known.
Made by lonelycross around 2012.

Read more at:
https://derpibooru.org/galleries/furrypony/10144
https://derpibooru.org/galleries/furrypony/10145

https://www.youtube.com/watch?v=Z1LTK1DOtAo
https://www.youtube.com/watch?v=JmqGIsR9PVE

Archive: 
https://docs.google.com/file/d/0Bw-pB5KgxU2BYzhkSjdqend1Nzg/