Each of the main story's chapter is around 4 to 5 minutes of play-time. The time for clearing the main story is about 50 minutes. Total play time is about 2 hours.
How to play
As the story goes on, you will meet with more people involved in the incident and more information about it will be provided. However, if you are not reading carefully, you will reach a "DEADEND".
To avoid "DEADEND", try to change your action in the story and investigate suspicious places. If you tap a correct point, you can advance to the next chapter.
You are recommended to read the sentence carefully to find out the strangeness hidden within the dialogues. There are also hints and answers so need not worry about stucking in cetain chapters.