Many small systems work together to make the detective experience more engaging.

Gifts are more sometimes useful than words.
At the start of the game, you can choose up to five objects to bring with you. Those objects can be used as gifts when talking with people.

The prologue provides short descriptions to set the scene.

Characters have blood type: they are either A, B, AB or O. When evidences of blood is found, blood type can be used to quickly filter potential suspects.

Some show relationship of the victim. Others are items and photos found at the crime scene.
Not all evidence leads to the correct direction.

The map provides an overview of the geographical locations. It also allows you to travel to different locations. There are three things that can happen at a location: meeting people, finding new evidence, or collecting items.
People have different schedule and you may only meet certain people at specific time of day.

There are two ways to start a talk with people: you can either bring them to interrogation which costs days, or meet them on the street.
Not everyone is available for bringing to interrogation - sometimes you must find them physically.

You can give people gifts when talking to them. However, it's important to know what they like first, and only give gift when it's the appropriate timing. It's less effective to suddenly bring up gifts to a stranger.

The last step of A Detective Game is to make conclusion of who do you think is the culprit. This is done by naming the suspect in court room.
The game can still be continued from this point, e.g. in case you want to chat with other characters.