As everyone knows, ALttP enforces a very linear order of the dungeons (at least until you’ve played a large part of the game). This minimizes the exploration aspect to a large extend. The goal of this hack is to remove the linearity as much as possible, without changing anything substantial. In fact, the author very much aimed at the changes being completely unnoticeable if not invisible.
Obviously, it would not make sense to allow access to everything at any time. There are a few necessary “sync points” for the story: Link needs all pendants to get the Master Sword, to fight Aghanim, to transfer to the Dark World. Link needs all crystals to access Ganon’s tower. Etc. Thus the goal is to allow an “as arbitrary as possible” order for getting the crystals and pendants, respectively.
