All first five titles in the Touhou series can only run on PC98.
The sixth title is the first one to run on windows.
There was also a large amount of revamp of the settings, backgrounds and characters. The first 5 titles have settings so different their stories are rarely considered canon now.
There was also a large amount of revamp of the settings, backgrounds and characters. The first 5 titles have settings so different their stories are rarely considered canon now.