King Neptune's Adventure came in three (3) variants:
This game was also one of the few Color Dreams games released in Europe. The box publishing information was simply French text typed on paper and glued to the back. The manuals were the same way with the text glued to the back of the manual.
King Neptune's Adventure, along with Menace Beach and Challenge of the Dragon, were released in a "competition" form. The boxes (as shown above) would have a gold sticker on the front and the back-label of the carts would have a long description of the rules. The objective of the competition was to find the hidden pot of gold in the first level. Even today, the pot of gold has yet to be claimed. The competition form of the boxes/carts are very rare.