Ao Oni (青鬼, lit. 'Blue Demon') is a freeware horror game developed by "noprops". It was first released in Japan in November 2008. The game was later adapted into a series of light novels and manga by Kenji Kuroda.
Plot[]
The story follows a boy named Hiroshi, who along with his school friends, investigates a deserted mansion that is rumored to be haunted. Upon entering the mansion, the group discovers that it is home to a mysterious creature referred to as the Ao Oni (青鬼 in Japanese, literally "Blue Demon") a tall humanoid with a deformed face that proceeds to chase the player throughout the mansion. The player must solve a series of puzzles while evading the creature to escape the mansion.
There are four different versions of the game, each with their own puzzles, maps and endings. Only the two latest versions have been officially translated.