In Perfect Assassin, the main character is an interplanetary assassin named Charon who has lost his memory somehow. Charon is contacted by a shadowy character named Ul D-Grak, who claims to have a mission for him, and asks the assassin to meet them on the planet Kar-Naq. Charon lands on the planet near a city and proceeds to search for his mysterious client.
The gameplay is from a third-person view, but the camera is always located at a set place on a map. As the player walks between different places, the camera fluidly moves from one set viewpoint to another.
The gameplay has some action in it, but mostly it is adventure-style solving of puzzles or talking to people. During conversations, Charon can ask people a question about any subject he has heard about (a character, location or item), and he can assume one of three stances: meek, normal or aggressive. This is sometimes necessary to progress in a dialogue: for example, certain characters won't give Charon necessary items unless threatened.
At other times Charon needs to use violent force to proceed. Charon can shoot his gun anytime, aiming at any spot visible on the screen. The gun can be used to kill enemies, or to shoot at specific parts of the environment to solve puzzles.