Snow Day! is a rules-light, lighthearted, primarily narrative game. Characters are children exploring an ephemeral winter wonderland that freakishly occurs in Hawaii. Characters are defined by a single Attribute: Age. Action resolution uses a single d20 roll. The game supports two categories of actions - Fantasy Actions and Reality Actions. To succeed on a Fantasy Action, the d20 roll must be equal to or less than Age; to succeed on a Reality Action, the d20 roll must be equal to or greater than Age. Much of the game revolves around the construction of fantasy snow monsters, imbued with fantastic capabilities.