Princess Peach's Castle/Rec Room

The Rec Room is a room found in Super Mario 64 DS, accessed in the room that leads to the Princess' Secret Slide and the character doors. It is a colorful room filled with props. The walls are pink, the floor is white with red, green, yellow and purple dots. There is a cabinet, a red ? box, a yellow ! box, a Bob-omb, a Power Star plushie, a 1-Up, red and green Koopa shells, and other items scattered around.

The room has a Toad in the center, who must be talked to in order to make the Rabbits begin to appear. The keys the Rabbits dropped can be used in the Rec Room in order to play minigames.

The Rec Room has the painting to Sunshine Isles, as well as an 8-star door that leads to a room believed to belong to Princess Peach. It contains a glass window that shows Peach's Balcony, a couch, and the entrance to Goomboss Battle.

Waluigi Connections
The doots in this room on the floor are red for Mario, green for Luigi and Yoshi, and yellow for Wario. However, there are also purple dots. Some believe that this implies Waluigi's existence, as they are prevalent in Super Mario 64 DS' multiple rumors. However, unlike most signs of Waluigi, these dots don't contribute to many rumors, instead just being used as a sign that Waluigi is in the game or was planned to appear in some capacity.

Super Mario 64 Manifestation
The Rec Room has been reported to appear in some personalized copies of Super Mario 64. They usually only contain the entrance to Sunshine Isles, and has a star-giving Toad, as well as the Goomboss Battle entrance. It is believed the minigames are not included due to lack of space on the cartridge.

Peach's Balcony
Peach's Balcony is a balcony that can be seen through a window in the smaller room in the Rec Room. It cannot be accessed, though some have theorized a possible way to reach it. Some say that you have to somehow use Wario's Power Flower ability to break through, or Yoshi's eggs. Upon shattering the glass, what exactly is found in the area revealed by the balcony varies. The most common report is that it doesn't lead anywhere, simply revealing that the hills are green polygons instead of actually revealing anything hidden, just like the model of the castle would indicate. However, some claim it leads to an anomalous level, such as Rabbit Meadow, or a hidden 151st star, which is usually involved with stories on how to unlock Waluigi.