Тhe player takes on the role of an unjustly executed man, who pleads to the devil to spare his life at the moment of his demise. The devil (explicitly referred to as 'Satan' in the manual) grants his request, and gives him command over the 'Castle of the Damned'. Soon after taking control of the castle, many visitors soon find themselves drawn to the fortress: some for power, some for salvation, and some for something as simple as shelter.
The player has the option of either destroying the intruders or letting them escape, but both choices carry consequences: for example, the player may choose to either kill two parents, who are out to find a cure for their ailing daughter, or let them escape to inform others of the demonic presence invading the mansion. Additionally, killing intruders is sometimes the only way to proceed and gain more Magic Points (earned by taking the victims' souls) or gold (earned by killing the victims).
https://en.wikipedia.org/wiki/Tecmo's_Deception:_Invitation_to_Darkness