The year is 1347 and a disaster is about to occur. The Black Death has reached our continent and after a number of years a large part of the population in Europe and North Africa has died. In Rattus, players settle in various areas in Europe and North Africa as the plague continues to spread.

During the game, the players receive help from the different classes from the Middle Ages. The farmers ensure population growth, the wise monks ensure that the rats stay away, the rich merchants flee when the plague approaches, the knights' warfare spreads the plague to new areas, the witches control its spread with the help of of magic and witchcraft, while the kings prevented the plague by staying in fortified palaces. However, the plague makes no distinction. When the rats come, no one is safe. When the plague recedes and the game ends, the player who was able to best keep his population alive wins.

In Rattus Big Box you play not only in Europe, but also in Africa thanks to the extensive board. In addition, Rattus Big Box contains the Pied Piper expansion, the Africanus expansion, the Academius expansion and the brand new Guilds and Inns expansion. As if all that wasn't enough, the Rattus Big Box also contains a bonus module. Because all expansions can be combined with each other, Rattus can be played in endless ways.