Hallowmoon, also called the Feast of Sun and Moon, is an event that appears in the Xbox 360/PlayStation 3 version of Sonic Unleashed. It is an annual festival in Shamar where the residents switch their diurnal and nocturnal routines to honor the Moon and the morning sun.
"Hallowmoon" originates from the Shamaran custom of giving thanks to everything they see and their worshiping of the Moon and Sun. Believing in the philosophy that there cannot be morning without the night, the people of Shamar observe Hallowmoon for an unspecified period of time each year as a way of giving thanks to the Moon for bringing forth the Sun each morning.
During Hallowmoon, it is customary for the people of Shamar to pay their thanks by switching their daytime and nighttime routines, meaning they perform their daily activities at night, and sleep during the day. When the Moon comes out, the people of Shamar say their prayers to it, expressing their gratitude to it for bringing forth the morning and watching over them.
Despite being a meaningful celebration, the personal dedication to Hallowmoon varies between people. People such as Labib find Hallowmoon annoying because it messes up their daily routines, while others like Utba are so devoted to Hallowmoon that they spend all their time praying, leaving them extremely sleep-deprived. Regardless of personal opinions, however, all the people understand the importance of Hallowmoon and overall accept the traditions.