There are many different versions of the original Ao Oni game, all created by noprops (pixiv / twitter ). The original game was made in RPG Maker XP, a paid software for creating RPG games, and many fan versions also used this software for authenticity. You will need to download and install the Runtime Package (RTP) to play games made in RPG Maker XP. The Installation guide has more about this in detail.
The oni genre has spawned many fan-made games. Most of these games were created in variants of the RPG Maker program, such as RPG Maker XP, VX or MV.
|Version 1.1||November 2008|
|Version 3.0||March 2009||Link|
|Version 4.2||August 2009|
|Version 5.2||September 2009||Link|
|Version 6.03||July 2010|
|Version 6.23||November 2011||Link|
JP = Japanese , EN = English, GE = German, IT = Italian, KO = Korean, CH = Simplified Chinese, TH = Thai, PR = Portugese