Severed Head PK (生首SC) is the name of a scrapped Famicom game for Yume Nikki. While little is known about the game, it is theorized it would have been a second game to be played in Madotsuki's real-world room, accompanying NASU.
Discovery
The only public evidence of Severed Head PK's existence is through the Thumbs.db image files found in version 0.04 of Yume Nikki. This version of the game was previously considered lost until it was dumped online by Gatobot of team #LaInvestigaciónYN on October 20, 2018.
While the Thumbs.db images found in v0.04 showed lots of unused or old content, the Severed Head PK images were some of several images that did not have a counterpart or final version seen in versions after v0.04. Reconstructions of the three images found to be related to Severed Head PK were made.
Gameplay
Nothing is known about the gameplay of Severed Head PK, as no playable version exists, though some theories can be formulated from the available Thumbs.db images.
One of the images appears to depict the game in action. It displays a grassy field, a soccer net, and a monochrome severed head on the field. A black bar with red text stating "PUSH ENTER" is also present. From this image, it's likely that the goal of the game was simply to get the head into the soccer net, which could be done by pressing the Enter key.
Another image shows a select screen, though it appears to be empty save for a title and a mountain-like background reminiscent of other ones in the game. It is unknown what the player was intended to select on this screen, though it may relate to difficulty, stages, or the severed head's appearance.