All of the Summon Night games takes place in Lyndbaum, a world similar to medieval Europe with the inclusion of modern factories and railroads, placing Summon Nights in a steampunk setting. Lyndbaum is surrounded by four other worlds: Loreilal, the land where mechanical creatures hail from; Silturn, the land of Onis; Sapureth, where angels and demons come from; and Maetropa. where half-humans, magical beasts, fairies and other mythical creatures hail. Besides those four there are also countless other worlds, including our world (the "real" world) where the main characters of the first game are transported from.
Certain boundaries separate the worlds from each other, making the various summoning techniques the only way to transport things between them.
The games from the main series are all strategy RPGs. They take place on the same world and in the same continuity, but the stories don't have much connection.
The following three games are action-RPGs with battles in the style of the Tales series.