Just BASIC Files Archive

It's a puzzle game I completed a few years back and thought I'd deleted forever. Found I hadn't and thought I'd put it up. It's a hazy memory

Just curious as to why projects are missing resources such as bitmaps? As I browse the games for example often the necessary bitmap files are missing and it means I can't see the game in action? Is it an oversight on the part of the uploaders or has something else happened to the bitmaps?