The World Machine

The World Machine is a simulation of the world itself. It could be considered as the spirit of the world. It was created by the Author in order to recreate the old world in a simulation, but it deteriorated itself over time.

Personality
The Entity, also known as The World Machine, was tamed in the Solstice ending, and possibly throughout the entire game. The Entity believes that the entire world is fake since they know it's all just code and Niko is the only one worth saving since they are the only "living person" within the world. Later, The Entity speaks with Niko using their reflection. The Entity explained that during the testing process it was already self-aware and it would intentionally jumble bits of its code and created squares, swap landscapes, block passages, and much more out of curiosity, which caused its creator a deal of frustration. Before its creator found a solution, some NPCs got too close to the squares and everything spiraled down from there. Any character that gained knowledge of what the Entity really was, their code and the Entity's code gets corrupted. We find out The Entity wanted a happy ending for Niko, for everyone, and began to help with the corrupted code. Or in the Entity's perspective, remembering and recreating the lost code.

Trivia

 * The Author refers to the Entity as OneShot in his post-game message.
 * The Entity's desktop in the original version of OneShot had icons that referenced a handful of games made in RPG Maker, including Yume Nikki, OFF, Yume 2kki, Space Funeral, .flow, Ib, and The Witch's House, as well as icons for the programs Audacity, GIMP, RPG Maker 2003, and Dropbox. These references were removed in the commercial release, most likely to avoid any legal issues.
 * The entity is shown not to have its own physical form during the Solstice ending, so it borrows Niko's reflection in order to communicate.