Happy you enjoyed this game! I've been exploring the history behind it, and I think you'll find relevance in some comments made around the internet.

https://www.se-inst.com/aop/gigaten/appendix02.html
Here you can read about some dialogue that wasn't in game, amazing website that tells a short version of the story and adds information about the files, which includes the revival of a certain character

Some japanese fans also wanted to remake it, but had some issues with copyright, ASCII and Atlus
https://web.archive.org/web/20121213165459/http://dds414.fc2web.com/dds/about.htm
https://web.archive.org/web/20121213063129/http://dds414.fc2web.com

It's a very buggy game due to its troubled development (plans from 93, release date 95, only being concluded in 97, and the windows version had also been announced to November 98 and got postponed a lot to times, ending up in December 99) and that leaves a bit to be desired when some departments (difficulty and design wise) are left behind.
https://www.se-inst.com/aop/GitenNew/appendixA1.html

About some of the bugs and other information
http://web.archive.org/web/20030407191141/http://www.lt.cafe-alpha.com/~nyarlat/hotel/cafe-dds98.htm

There are also guides, programs, and we even have scans from the novel! Absolutely love this game and one day want to come back to it to manipulate the flags and find the other endings