Visual novel today is a very broad genre.
For me it depend on what they include the the game.
Some VN like kanna sister simply just a kinetic novel with branching story line similar to goosebumps in that case i really cant say if those classified as game
Meanwhile some other VN implement actual gameplay like Senjou no folklore, Hyakki Yakou, Baldr Series (Giga), Dai- series (Alicesoft) and Meister Series (Eushully).
My suggestion is instead focusing on the VN itself you should focus whether or not gameplay is exist within the game or not