Sometimes you just need to express your dark side. In Dungeon Keeper, you're the boss of a horrible, rotten-smelling dungeon, and you must keep all of your loathsome, demonic creatures in line. If that weren't enough to keep you busy, your lair is continually invaded by hoards of idealistic "heroes" wanting to slay you, proclaim a triumph over evil, and go back to a village feast in their honor. What's an evil boss to do? Unleash your minions, set deadly traps, cast spells, and punish them with your torture devices. And most of all, teach those dumb do-gooders a lesson.
An absolute masterpiece! There are some problems when trying to run on a modern system, which KeeperFX mostly fixes. The only real problem I have is that the engine has the fps locked to the game tick rate so you can't play at 60fps (unless you want the game to run over 2x as fast).
The gameplay itself has stood the test of time really well and all of the levels are distinctly unique and fun to play. There can be some bigger difficulty gaps sometimes, but nothing impossible.
I absolutely recommend this amazing gem!