Family Guy: Back to the Multiverse is an action-adventure game based on the TV animation series and specifically a sequel to the episode "Road to the Multiverse" from the series' eighth season. Players take control of Brian and Stewie Griffin as they try to prevent Stewie's evil half-brother, Bertram, from creating an army strong enough to kill Stewie. Players go through seven different universes with each having a unique ruler, ranging from the Amish to giant chickens. In addition, the game includes many characters and themes from actual TV episodes.
Players switch between Brian and Stewie at any moment in single-player mode, while cooperative gameplay is supported through a drop-in, drop-out system. The game offers both offline and online multiplayer options, where players can unlock costumes, multiplayer maps, extra levels, and other playable Family Guy characters as they progress.
The game is played as a third-person shooter. Stewie uses a laser gun and a flamethrower, while Brian wields a shotgun and a pistol. Upgrades are provided by collecting cash and spending it at the multiverse store. These upgrades include improved health and ammo capacity, among other benefits.