Well, they don't really refused. To quote Rafael Latiegui, "At the moment is not possible for us to deliver the source code of Igor.". This is from August 2004.kelmer wrote:
So you asked them and they refused to hand you the code? I'm shocked, I've contacted them a few times and they're nice people, I though they would collaborate with something like this...
Maybe we should try again?
And as it has been mentionned, work without the source code and only from disassembly isn't really possible. All the datafiles (room bitmaps, room mask, walkboxes, sprites etc.) are included in the executable. The game logic and the cutscenes are also completely hard-coded. And to finish with, the executable uses the borland overlay stuff, which just makes the disassembly harder to follow.