The hero of the game is Overlord, a great warrior, resurrected by predatory creatures - minions, to defeat the seven rulers of the seven provinces and capture their lands with all that is there. Overlord had a predecessor, who owned all the lands, but their present rulers defeated and killed him. And they fell into seven deadly sins, one for each.
The hero uses the old destroyed tower as a base. He brings there all the trophies and gradually transforms it into a comfortable, spacious and in every respect well-equipped room. Among the trophies are artefacts stolen from the tower, which add even new places to the tower, increase the health and magical power of Overlord.
Minions are of four kinds, each species has its own abilities. Minions perish in battle, but Overlord can summon new ones from special wells, paying for it with the life force of dead enemies. You can build a smithy and then buy and improve weapons there.
Overlord can behave differently, he is tempted by the same sins that enslaved his opponents. Its "corruption" exists in the game as one of its parameters, measured, displayed and affects the course and end of the game.