Crusader Kings II is a Grand Strategy game in which medieval conditions are simulated. You take on the perspective of a single ruler among many, i.e. not that of a uniform state. The character played has his or her own character traits and abilities, such as the art of war, administration or diplomacy. You can choose freely between rulers of different ranks, such as counts, dukes, kings and emperors. The map stretches from Spain to India. The starting dates can be chosen between 963 and 1453, the end date of the game. You play a ruling family over several generations, always taking a leading role within the dynasty. The player is confronted with military, economic, legislative, political and dynastic problems. Two aspects are of particular importance. Most actions require a currency, namely gold, prestige or piety. In addition, each character has a value that indicates the personal relationship to its own character. These values influence diplomacy, which does not take place between abstract states, but between the characters. Even one's own empire does not function as a collective, but as an association of persons. As a ruler, you must always take other characters into consideration, whether they are your equals, superiors or subordinates. The continuation of one's own family is also central, since the game ends when it expires or loses all its lands. For this, the player must arrange marriages, raise children and secure the succession. This is regulated by a selection of inheritance rights that can be introduced under certain conditions. This game can be played in single player mode as well as in cooperative or competitive multiplayer mode. The gameplay is not noticeably different. Neither in single nor in multiplayer mode are there predefined goals, but these are devised by the player himself or herself.

The research interest in Crusader Kings II is focused on the area of historical knowledge acquisition. The focus is less on event-historical knowledge than on systemic and geographical knowledge. The research is therefore focused on three specific learning potentials: (1) in the field of (historical) geography, to which we attribute great potential due to the strongly map-based gameplay and the, by the standards of digital games, unusually accurate world map. (2) the game may give players an idea of medieval ruling practices. Unlike most grand strategy games, you don't play from the perspective of an anonymous state, but from that of a specific person who is part of a dynasty and a feudal alliance. It is therefore necessary to test whether this player's perspective enables the players to empathise with the medieval ruling structures, which are strongly based on personal relationships, such as marriages or feudal relationships. (3) it should be examined whether the extremely detailed representation of the Middle Alster in Crusader Kings II can give players an idea of the richness of detail and thus also of the diversity of the medieval world, for example, of the great heterogeneity of Islam. In practice, however, research on Crusader Kings II is determined by the extremely complex and not very beginner-friendly nature of the game, which makes experimentation very difficult. The target group is therefore initially limited to history students on Bachelor's programmes, who can be expected to have not only facilitating prior knowledge but also a certain enthusiasm for the topic. For this purpose, we designed a longitudinal study in which players are first introduced to the game over several sessions and can then play the game. In the process, both the players' increase in knowledge and their basic understanding of the Middle Ages are examined. Since the introduction to the game is complicated, the players are actively supported by the research supervisor, who has a lot of experience with the game herself.