What can I say about a game that let's you be a creature like a devil and kill good guys for a living? How about it's one fun game.
Gameplay - Here is what happens; you are a Keeper who makes dungeons to raise creatures to work in your army. Your dungeon heart is your life force. If it gets destroyed then you are banished from the realm. You need to collect gold to help pay to build your rooms and to pay your creatures for being in your army and to pay for their training.
The key is to build up a strong army and head out and kill all of the heroes and in some cases opposing keepers. If you kill an enemy their body will lay on the ground and eventually decay, but if you have a jail you can drag the body to the jail and then it will rise into a skeleton that will fight for you. If you have a torture room you can heal the slain foe and take them to the torture room where they may give you map informaton or turn and join your side. If you have a grave yard, the decaying bodies can be dragged to it and eventually a vampire will join your side. There is one thing to remember though, your creatures can end up hating each other and leave your dungeon.
Graphics - The graphics are pretty good for these types of games. Creatures look very smooth and terrifying in some cases. The rooms and dungeons themselves look just like you would want them to. The cutscenes are spectacular as with other Bullfrog games such as Theme Hospital and the first Dungeon Keeper.
Sounds - Hearing cannons going off and screams coming from the torture room are all that this game needs, but it comes with a narator voice that is perfect.
Replay Factor - There really isn't much in this area, but there is a skirmish section were you can keep coming back to and play.