The game's protagonist is a nameless young boy who while lost out in the rain sees the silhouette of a young girl. Upon following her, he turns invisible, like her, and finds out there are various other invisible creatures roaming about. He has to find his way to her among the world of the invisible.
Rain is an adventure game where you play as a young boy who is invisible and can only be seen when standing in the pouring rain. When walking under shelter outside the rain, the boy cannot be seen and can only be tracked by his watery footprints. The player will have to utilize the visibility of the boy, and other creatures, in the rain to solve various puzzles and tasks throughout the game.