An interesting fact about these games is that they are the first canon Zelda games created with third-party involvement. It was originally titled The Triforce Series and was intended to be a trilogy of games with the same premise of linking the games together (in any order) to form one solid narrative. However, complications and budget forced a reduction to two games. In addition, one of the games was intended to be a remake of the first Zelda game, which was reworked into Oracle of Seasons after the Triforce Trilogy was cancelled, explaining why Holodrum's game map was similar to the map of the first Zelda game.
What Could Have Been: The trilogy's first release had noted that things were connected in such a way that there would originally have been three games with linking portions. The third game was eventually cut, one of the main reasons being that it would make the linked game feature far too complex.
Oracle of Light / Mystic Seed of Courage was to be the third one and would dealt with actual dimension travel between a 'dark' and 'light' world; each representing a split in a time line (Ages and Seasons caused by some time ripple) that would have lead Link to the realization that he was actually in the same world but one had a lack of color and the other had too much.
Accordingly the color had a way of changing the dark world and the light worlds respectively by giving/taking it away to open paths, move doors, and even repainting reality.
One of the Mystic Seed games was going to be a straight remake of the original Legend of Zelda. Its assets were reused for Orace of Seasons, which is why so many of that game's bosses are taken from the first game.
Hyrule Historia reveals artwork for Ganondorf, who only appears as a mindless Ganon, meaning it is likely he was to appear.