A very interesting prequel, honestly couldn't even tell it was fanmade. I'd recommend playing it right after Rebuilt, since the two share almost identical mechanics and map layouts (I'd assume this holds true for the original PC-98 release as well).

The game is incredibly short if you just wanna play through the main content, only took me about half an hour completely blind. Unfortunately, you're required to go through every bad-end on a single save to unlock a good bit of extra content, and that took much longer even with a guide. Still only took about two hours overall, so I guess it's not too much of a complaint.

Either way, if you played and liked the original/Rebuilt, can't go wrong playing through this one.