Nazo No Masquerade

Nazo no Masquerade ("Mystery of the Masquerade") is a menu-driven adventure game for the PC Engine. It was developed by Riverhillsoft, a company best known for the JB Harold series of murder mystery adventure games.

The player is a detective staying in a mansion while investigating a crime on the premises in the early 20th century. They can move around the mansion via a map that can be pulled up at any time, and talk to various NPCs staying in the mansion's many rooms.