The player takes the role of one of the three Jack brothers – Jack Frost, Jack Lantern, or Jack Skelton – who have visited the human world for Halloween, and need to return to the fairy world before the portal connecting the two worlds closes. The player needs to make their way through six areas, which consist of a number of floors, defeating enemies by using character-specific attacks and collecting keys to be able to advance to the next floor. It received generally positive reception for its gameplay, but was criticized for the lack of puzzle elements and under-utilization of the Virtual Boy’s 3D effect.
Jack Bros. follows the three Jack brothers – Jack Frost, Jack Lantern, and Jack Skelton – who have traveled from the fairy world to the human world through a portal that opens every year on Halloween. Losing track of time, they spend too much time in the human world and forget about returning until there is only one hour left to the portal’s closing; the fairy Pixie shows them a shortcut, which, while dangerous, is the only way to return to the portal in time.
The player picks one of the three brothers to play as; Pixie can also be unlocked as a playable character. They traverse six areas within a time limit to make it back to the fairy world in time. The areas all consist of a number of floors; the player needs to collect all keys on each floor before being allowed to jump down to a lower floor. To find the keys, the player uses a radar that displays their locations; once all have been collected, it shows the location of the exit. Once the player reaches the bottom floor, they are faced with a boss character they need to defeat, after which they can proceed to the next area.