Apparently, Mia loved this game, which is why Darius had it on display at his office building shortly after her death in November 2017, as seen in The Last Yandere. At the time, that particular cabinet was believed to be the earliest stable version of the game, although it would refuse to work except in the presence of Lilith's brother.

This game has some mysterious connections with the TriNemesis and, by extension, the "tumor-like device" in Lilith's brother's brain.

Gameplay

In PROGENITOR DERE, you control a simple little character in a dark maze. The goal of each level is to navigate the maze and reach a diamond to progress to the next level. This is made more difficult by the fact that the maze layout always starts out in total darkness, and is revealed bit by bit as the character walks around. Occasionally, monsters lie in wait to ambush the character. Throughout the game, an artificial entity that calls itself AIRI speaks up, offering instructions and warnings to the player.

Plot

The game, as shown in The Last Yandere, has 13 levels. In the first level, AIRI introduces itself and its purpose. It also explains that collecting diamonds is the way to progress through the game. Later on, AIRI only gives vague warnings ("Do not let them get you.", "Do not die.", etc.). The connection between Lilith's brother and AIRI becomes evident during the final four levels, when AIRI says "There is a monster inside the TriNemesis." in the tenth level, and the particularly damning claim, "I know what you did. You killed her. You killed Mia." in the final level. After this, the TriNemesis appears, and a snake monster destroys the player character, causing the game to end in static.