The Day/Night system makes a return in Mario Party 6, and becomes an integral part of the game. The characters that represent this system in Mario Party 6 is Brighton the sun, and Twila the moon. The Day/Night system was expanded upon after its last appearance in Mario Party 2. The Day/Night system appeared on all Mario Party 6 boards, and the time of day changed every three turns. In this game, the characters were not able to control the time of day. The Day/Night system played a bigger role in the board maps also. Depending on the time of day, the characters could participate in different events, visit different characters, pay different prices for orbs, and even changed the method of obtaining the star. The Day/Night system adds more strategy to the boards, as the changes between time periods are more varied.
The Day/Night system also affects the mini-games in Mario Party 6. Most of the time, the new system simply changes the background of the mini-games depending on the time of day. However, it can change the objectives of the mini-games too. In the mini-game What Goes Up..., during the daytime, the characters must make their way up the beanstalk by jumping on Paratroopas and clouds. However, during the night time, they will be falling down the beanstalk, and must avoid the clouds and Paratroopas. The Day/Night system may also alter tiny features in the mini-games. In the mini-game Daft Rafts, a Spiny will appear on the rafts during the day, while Podoboos will appear on the rafts at night.