A lot of game worlds have the memory of somebody walking into a room and immediately forgetting why they’re there. The player breaks into a secure facility, empties every cupboard, knocks out twelve guards, destroys the security system and leaves through a window. Five minutes later, the guards have returned to their original positions, the building is operating normally and somebody has apparently restocked every cupboard during an active emergency. Games can’t remember everything the player does. Recording every moved chair, opened drawer and disappointed shopkeeper would become expensive, complicated and a wonderful way to make the save system begin quietly smoking. However, a world should remember the actions that matter to its fantasy. When behaviour changes the state of the simulation, decisions gain weight...
