In Impire, the player takes the role of the mighty demon Báal-Abaddon - or at least he was mighty until he was summoned by the incompetent magician Oscar van Fairweather. Now he has the form of an imp. The goal of the game is to regain the powerful demon form; the story is told in humorous dialogues.
Each level plays basically the same: the player builds up a dungeon by placing pre-defined rooms in the playing area - certain important rooms like the treasure chamber are already in place. The worker units are imps which are used to build the rooms and exploiting mushroom deposits which are one of the three resources (the other being material and gold). Resources can also be earned by sending squads to overground missions. Those are assigned on a special map and simply mean that the squad are unavailable for a set amount of time.
Other rooms have practical purposes, e.g. training rooms or the kitchen (fills up the units' aggressivity, i.e. strength). While units can walk on their own, it is much faster to manually teleport them to their designation; this means there is a lot of micro-managing involved. Up to four units can be assigned to a squad. Of course no dungeon is complete without heroes trying to rob it: ladders randomly appear over the dungeon. Only when they are destroyed fast enough, the heroes actually use the front doors. Defeating enough heroes earns DEC points which are in turn used to unlock more rooms and units. Each mission starts from zero.