Overlord (1992)

As the dictatorial ruler of the Epsilon Galaxy, the player has obtained complete, indisputable authority. However, during a scientific experiment in hyperdrive technology, Epsilon scientists discovered four "buffer" dimensions, each containing a number of barren planets that exist between the Epsilon Galaxy and another alien dimension. Unfortunately, the most powerful empires from these alternate dimensions have also just discovered these zones through their own experiments. The player must battle these alien species for control of these buffer worlds, to ensure that their rule in the Epsilon Galaxy remains intact.