Dungeon Keeper level 19: Mistle.

Difficulty: Very Hard.

Your Portal max: 30 creatures.
Enemy Portal max: 32 creatures.

Starting forces: 8 Imps (4x 5th, 4x 10th level)
Enemy's starting forces: 6 Imps (4x 3rd, 2x 10th level)

Starting gold: 3000
Enemy's starting gold: 800000

Possible minions:
You can attract: Troll (up to 6), Dark Mistress (up to 2), Bile Demon (up to 1), Demonspawn (up to 10)
Enemy can attract: Warlock (up to 1), Skeleton (up to 20), Spider (up to 10)
Can be found elsewhere in the level: Dragons (2x 4th level), Vampire (1x 4th level), Enemy Heroes to capture, torture and convert to your side (1 shitload).

(Note: Technically, the player is able to attract Dragons, Flies, Beetles and Hellhounds as well - but there are none in the creature pool for this realm, so none will ever show up. Also don't expect to see Demonspawns any time soon...) Rooms:
Known at start: None (!)
Can be built, once you have found them: All.
Can be researched, once you have found a Library, to save you the bother of finding them:
Everything EXCEPT Training Room (!!!)

Spells:
Can research: Sight of Evil, Speed Creature, Call to Arms, Conceal Creature, Hold Audience, Cave-In
Can be found elsewhere in level: Heal, Protect Monster, Lightning Strike, Destroy Walls

Doors/Traps:
Can be manufactured: All doors and traps.

Enemies: Heroes, and one enemy Keeper. And the sheer bloody-mindedness of the game designers.

And you thought the last level was hard? Think again.

You've bobbed up into a deserted, previously-occupied dungeon. You start off not knowing how to make any rooms at all: but if you could somehow find and claim for yourself any given room, from that moment on you can build as much of it as you want. Furthermore, if you find a library, you could research any other room you wanted. With one important exception... which happens to be the one type of room missing from the abandoned dungeon you just stumbled into. One of the most important rooms you can have, and you can't research it, and it isn't here to be found at the beginning of the realm.

NO TRAINING ROOM. AARGH!!!

The limited number and types of creatures available in the realm is also a serious handicap. All you'll get, at first, are Trolls (six of them), Mistresses (two) and Bile Demons (one). Of course, you can create as many Horned Reapers as you want: when you sacrifice creatures (or when they die in other ways), they go back into the generic creature "pool", so you can keep on sacrificing your single Bile Demon (and the rest of them) and getting him back... so you can have a whole army of baby Reapers. Trouble is, even baby Reapers are expensive to maintain: but without a transferred creature, you'll need them.

You want control of those rooms - fast. And it's faster to dig through the walls than hammer down the doors (unless you managed to transfer in a big-hitting melee creature from one of the Secret Realms.) One bit of good news: when the previous owners cleared out, they left somebody behind in the graveyard, who'll join you to help research. And you have your Trolls and Mistresses, and the Bile Demon too, to work in the workshop and sloooooooowly grind out the traps and doors. Which you're going to need.

Because at some point, you're going to have to let the big wide world in. And since you haven't got a training room, you're going to have to beat up creatures and convert them... swarming more powerful creatures by the weight of numbers of your level 1 and 2 creatures (if you have baby Reapers, they will be of considerable help. Pay them by hand and let them use your Temple in between times. Or chuck them back into the Portal before pay-day and create a new lot after pay-day - you haven't wasted any gold on training them, after all.) Worse still, the first few foes you capture, you're going to have to convert without the Heal spell: so you'll have to feed them chickens by hand to save their health in the torture chamber. The annoying thing is, you can't let them starve into Skeletons... the enemy Keeper starts with a ready-made Scavenger Room, long before you've had the chance to research it (there is no scavenger room in your dungeon), and he has more skeletons than will fit in his training room. Any skeletons you make will be scavenged before you have a chance to move.

Whichever direction you go in - east or north - you'll run into trouble straight off. Either way you need to have made some doors beforehand so you can separate the enemies as they come for you, and take them one at a time, because it's only by sheer weight of numbers against one creature that you can hope to prevail. (Hint: This, of course, does not apply if you have transferred a powerful creature from a secret realm, who can survive multiple hits from weaker creatures - which makes this phase of the level a whole lot easier.)

The area to the east is perhaps better tackled first, as that is where the gems are: and since you have a vampire, who is expensive to maintain (things will be even more expensive if you have baby Reapers), you really need gold. It's a very linear section, with Tentacles, Archers, Wizards, Fairies and Monks. The dangerous encounters are the ones where you have to take on three or four foes at a time - try using doors to separate them: others can be let in just one at a time. Eventually you'll reach a T-junction along the bottom of the realm: to the right are the gems, and to the left is a heavily trapped corridor leading to two imprisoned Dragons (who will join you) and a Resurrect Creature special.

(IMPORTANT: When you get control of the gems, always keep the Treasure Room in your OWN dungeon stocked with gold, so that your minions will only have a short walk. Otherwise, if it's empty, your minions will walk the long and winding way to the treasure room you built by the gem block - if they're hungry on the way there, they may even starve to death.

To the north of your own dungeon, you'll have to let in first a Fairy and then two groups of 4th-level Barbarians - the latter will prove problematic foes early on, although a swarm of baby Reapers (no, NOT a swarm of Horny babies, you twisted person) will probably take them down. There's an open area containing the Heal spell, seemingly undefended: but the moment you enter it, you'll be ambushed by thieves. It would be nice if you had some at least of the Barbarians on your side by then. (In fact if you can get control of the Heal spell early, you do yourself a big favour when heading eastwards... although it costs you more gold at first, to use the heal spell.) Some more Barbarians await behind a door further north, leading to the hero castle in the northwest.

Use the water as corridors, rather than tunnelling around it. Bridge over it, and place a Guard Post every tile adjoining YOUR side of the water. That way, if you knock down a wrong door and too many enemies come at you at once, you can sell the bridge in the knowledge that the enemy cannot enter your dungeon by climbing up onto a Guard Post out of water. The one thing that you do not want is the hero castle connected to your dungeon by land. (If you can expand your workshop to a large enough area to build Lava Traps, then a series of two lava traps in a corridor with a guard post on your side of the traps will achieve the same effect.)

Dig along the southern edge of the permanent rock. When you encounter a pool, put a guard post adjacent to it, just in case you break into the enemy dungeon by mistake. You don't want to be connected by land to the enemy dungeon, for the same reason that you don't want to be connected to the hero castle: but there are two Steal Hero bonuses in lakes along the permanent rock. Build bridges under them, have them taken to your library, then back out and sell the bridges.

(Hint: If you're REALLY lucky or really fast - most likely if you broke out of your dungeon to the north rather than the east first - there's a chance that if you head straight north and tunnel around the north side of the northeast corner, that the enemy keeper has not made a move for the most northerly gems yet. Use Sight of Evil to find out, and you may find it worthwhile to try for control of them and fortify walls to keep him out. Who dares, wins...)

Either way, at some point you're going to have to take on the hero castle - some or all of whose layout you should know by now, from torturing all those heroes. You may even know what types of heroes there are. Judicious use of the two Steal Hero bonuses you found may help greatly. Once you walk past a certain point in the castle, the Lord of the Land and a party of samurai will drop in. This would be a good time to use at least one Steal Hero, if you have saved one: ideally, you want as many as possible of those samurai, alive - samurai are great minions if you keep them away from your (two) mistresses. Capture the ones you can't steal.

(Hint: We already know the enemy has a scavenger room - but perhaps YOU could make use of one, too? The only hero that cannot be scavenged, or stolen with Steal Hero, is a Knight...)

Once the Knight and his party are dead or converted, you can claim the rest of his castle - and, once you've destroyed his Heart, which is between you and the relevant areas, you can at last take control of a couple of TRAINING ROOMS (at last!!!) and then build your own training rooms for your creatures. Don't forget to pick up the Destroy Walls spell too, just in case the enemy has walled himself in.

Now you can train your minions up to a decent level, at last. And if your head count ever falls below your portal max of 30 again, you can at last attract Demonspawns (who require a training room to be attracted) and train them into Dragons to bulk out your numbers up to 30 again. Take the fight to the enemy Keeper, stomp him flat and stick his head up on a spike. Wasn't that satisfying?