The game involves building a dungeon deep in the earth. As you expand your dungeon, you gain gold and mana, that you use to build more rooms, traps, and other fun things to increase your power. When you have gained enough power, you find the lord of the level, take his sweet little head off, and watch as the aforementioned demon, Horny, grabs the magical gem for you. The play involves balancing how much gold and mana you have with the needs of your creatures and your final goal. If you spend too much of your gold on more rooms, you may not have enough for building traps to defend yourself from good. If you spend all your mana on building imps, the construction workers of your dungeon, you may not have enough mana to heal your dying creatures or fire your traps at marauding adventurers. And through it all, you have to carefully plan the layout of your dungeon. Your creatures need food, places to sleep and train, entertainment, and many other things. If you don't control them well, you may find your creatures leaving your dungeon for greener pastures.
Dungeon Keeper II has a unique feel all its own. It is not the straight resource building then attack play of Warcraft. Because you are carving out the map by tunneling your dungeon out of dirt, you have many more options of defense and offense. You can set up elaborate traps by guiding your enemy down narrow corridors with Indiana Jones style rolling boulders at the end. You can avoid you enemy's defenses by mining around them. You can do many things normal RTS games don't have in them. Overall, we think most people will still prefer the play of Starcraft or maybe the upcoming Command and Conquer: Tiberian Sun, but the play of Dungeon Keeper II holds many interesting things and is plenty of fun.
The great thing is, you get to do all this as the bad guy. You are the dungeon keeper. You're not the grand high and mighty hero. You're the filthy evil slime that crawls through the sewers and undermines the city. You are vile scum, and it's never been this good to be this bad. If you get Dungeon Keeper II, please give your imps an extra slap just for Sharky. Actually, just slap the little buggers to death for us.