Source: http://blog.goo.ne.jp/gekigangar/e/b1ffebf2a2558aa4461791a0c1bf9362

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It's amazing how much of the series they had planned out from as far back as 1989.
My particular "wow" moment was a quiz in Rance II where to know the answer you have to have played either Kichikuou Rance or Sengoku Rance- KR wouldn't come out for another six years and SR wouldn't come out for another sixteen years.
If you hadn't played those games yet you could still get past that part of the game because it was a multiple choice question, but the idea of putting a challenge in a game that becomes easier if you've played a game that doesn't exist yet just speaks to the intense level of planning that Alicesoft and TADA specifically poured into the series.
The games aren't perfect and I would say the majority of them are bad, some of them very bad, but the overall journey the series takes you on is incredible in scale- not only one of thousands of hours of JRPG, but of dozens of years of gaming history.
If you like JRPGs, have a lot of free time, and haven't tried the series yet, I really recommend it. Sengoku Rance is one of my all time top favorite video games and I've played it alone for well over a thousand hours.

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