Overlord: Raising Hell single-player expansion pack opens up a
series of hellish new levels. Complete with new enemies and
objectives, each level is a supernatural abyss - a hell for each
of the game's five kingdoms: Mellow Hills, Evernight, Heaven's
Peak, the Golden Halls and the Ruborian Desert. Access to each
abyss is via a portal, which opens once a kingdom has been
successfully conquered and the previous ruler banished to a
personal hell within. However, it's not just the fallen heroes
that have been dragged into the abyss; the Overlord's newly loyal
peasants have also been taken down into hell too.

With the undead denizens of each abyss on the attack and
threatening the Overlord's reign above ground, there's only one
thing to do about it: assemble a minion army, descend into each
abyss and embark on a fresh wave of tyranny in order to return the
serfs to their homelands, defeat the fallen heroes once and for
all, and claim the throne of each kingdom's underworld.