The Dark Mysteries Campaign Grand Game follows the course of events between the end of the Dark Mysteries story arc and the beginning of the Next Generation story arc. However, this period of time will be gamed at a state level, not an individual level. Each of the players of the Grand Game will control one faction (a small kingdom or a significant district of a larger kingdom - for simplicity sake, the term "faction" will be used for both), directing that faction as the absolute leader. The factions that are in play for the Grand Game are listed under Grand Game - Factions.

One turn in the game represents one season, and the game itself covers fifteen years, so the game consists of sixty turns (four seasons per year x fifteen years). Each turn, players choose actions for their faction to execute - these can range from developing land (increasing Territory) to espionage to attacking a neighbor. Actions are discussed more under One Roll Engine. See also Grand Game - Turn Sequence.

Each faction is described by a set of five Qualities. These qualities are relative measures of how effective a faction is. The scale is not linear - a '2' is not twice as good as a '1' - but it is more like an exponential curve. Refer to Qualities for more details on a faction's Qualities.

The game uses the One-Roll Engine (ORE). Specifically, the game uses the Company rules in the Reign Enchiridion. Each action a faction takes uses a pool of d10, with the goal (normally) to find the best number of matches, with a pair being the minimum. Refer to One Roll Engine for more details. One detail to note - the minimum requirement for success on a roll is a pair, so any task roll that only has a single die available will automatically fail.

Game play is determined as described in the Grand Game - Turn Sequence.