gaogao!_(four-nine)
GAOGAO! is an eroge game series developed and published by Four-Nine (フォア・ナイン ) for PC-98.
There are four installments, the latter three being post-apocalyptic:
* GaoGao! 1st: Radical Sequence (1994)
* GaoGao! 2nd: Pandora no Mori (1994)
* GaoGao! 3rd: Wild Force (1994)
* GaoGao! 4th: Canaan - Yakusoku no Chi (1997)