Year 1991 was the first with monthly issues and for that reason the hardest. Let's first try to determine its prominent features for VNs:
- Number of adult games increased greately to some 100 titles overall
- PC-98 era arrives with mouse support and the older systems finally lose support
- RPG percentage remains high at some 20% while ADV grows significantly to some 50%
- New sub-genres appear - point-and-click, quiz, board game.
- Some games start to use action icons instead of command selection thanks to mouse use.
- It's the last year without any government regulation. After November 1991 shoplifting incident regulations being created.
- Masterpieces of 1991:
1. CAL II
2. Cosmic Psycho
3. Cybernetic Hi-School Part 4 ~Ape Hunter J~
6. Jesus II
8. Nostalgia 1907
9. Psychic Detective Series Vol. 4: Orgel
10. Psychic Detective Series Vol. 5: Nightmare
11. Rance III - Leazas Kanraku -
Those were the games with great stories and a professional touch. And I'm biased here towards ELLE since it's the only one that got renewed version in 2000s. Otherwise it might be a serious competition.