I have to admit the game was short, but I think the only reason for that is because they made so many endings for it.
This may not be a good reason, but hey.. The fact they couldn't get a sequel or prequel going. lol also, for the PC, Konami didn't really have good support for it.
I think it's ashame the game wasn't as popular as what I might have expected. It's also ashame they have't done a sequel which I really wish for.
It's a puzzling game which gets your mind going with great character design and a good plot to it. Though it maybe short, you still have some many endings to figure out. Not only that, but Demon Homunculus is such a great, cool and sly charcater.