After the conclusion of the battle between dreams and nightmares, Mario escaped Bowser's dream world, thus returning peace back in the real world and not a single nightmare ever has invaded a conscious mind. However, there is yet another dream Mario has to face: a green comet has fled by scattering green stars around the dream worlds and nightmare worlds over. And now, Mario must once and for all search these hidden treasures.

Will Mario be able to enjoy his dream... or fear another nightmare?

Mario's Nightmare 64: Green Dream is a major ROM Hack made by LinCrash & StanFuzz. It is an extension of the original Mario's Nightmare 64 created by Apioeus, as it follows the concept of Green Stars from Super Mario Galaxy 2, placed at several, tricky locations in existing levels.

Compared to the original 140 stars, this game contains 130 brand new stars in which a special reward will be unlocked and is accessible after collecting all of them. Also, various quality of life improvements are featured: rotary parallel camera, infinite lives, no fall damage, etc.

All the levels are accessible from the start without a single requirement; but the main difference is that enemies, hazards and bosses have been removed. Despite the major change, it is worth the difficult challenge in finding green stars and demands a lot of knowledge in platforming skill & sequence breaking.

All the courses have the same exact layout, but with minor differences. Some of the level names are changed, implying worlds are now harmless to the player--although most of the nightmare worlds still remain in activity.

The main world include 6 green stars, as signs and NPCs will help the player by giving tips in finding them.

The Cap Switch Palaces, as well as the Bowser levels have 3 stars, while the secret stages have 7 stars. Cap Switches are enabled by default but blocks are still available.