Players for each side work together in order to coordinate their strategies. The English start the game controlling all of England, but then the Viking players invade from the sea to strike deep into English territory! Players decide when to end the game by calling for the Treaty of Wedmore. The team controlling the most cities by the end of that round wins the game.

The mapboard represents the areas of England that were invaded by the Vikings in the 9th century. The English start with control of the entire continent, but every round, a new Viking leader invades from the sea and threatens to conquer England! Viking Leaders are a new addition to the familiar ruleset employed in the “Birth of America” series. Leaders bring huge waves of Viking Reinforcements, and they add exceptional mobility to invading Viking armies, allowing them to continue to battle and pillage as they move.

Unlike the “Birth of America” games that 878 Vikings shares many of its rules with, army units are represented with unique faction miniatures. There are unique models for all four playable factions, as well as the “Fyrd”, the peasant militia units that rise up to defend their cities when attacked.

All four factions and the Fyrd have their own combat dice. For each 'Hit' result rolled, an opponent loses one unit. For each “Flee” result rolled, you lose one of your units to the Fled Units box where it will return later as a reinforcement. For each blank face rolled, you have a 'Command Decision' and may use that to retreat a unit in the battle to an adjacent area.

Each faction deck contains Event cards, Movement cards, and one Truce card. Every turn, each faction will play a movement card to maneuver their troops and zero, one, or two event cards. When both factions of a side (English or Viking) have played their truce cards, the game will end on that round!

Each deck has a specific number of movement cards in it and managing them is an important part of the game. There are also special event cards that can be played on your opponent's turn, reflecting various historical events such as the conversion of some Vikings to Christianity or the infighting between various English kingdoms.