AI: The Somnium Files – nirvanA Initiative

AI The Somnium Files is a great VN with great visuals and settings. Good soundtrack as well.

It is more elaborated than a lot of games in the genre, as you have many scenes in 3D to explore.
The story is really interesting and has several branching paths.
It mixes very serious situations about murders and crime scenes with some humor to keep things light.
The character design is very good as well.

I greatly enjoyed the game and recommend it.