Unlike more modern visual novels, the emphasis was solving lots of puzzles to progress the story forward, rather than just read to progress. In it, you solved crimes by finding clues in different areas and inputting specific phrases/commands into a keyboard, similar to Choose-Your-Own adventure games that came before it.
The first ‘true’ visual novel was ‘Portopia Renzoku Satsujin Jiken’, which was released in 1983, which was influenced by American adventure games at the time.