Dungeon Keeper

All creatures, buildings, and traps:
At the Main Menu, type please give all.

Moon Levels
Some levels only show up during a full moon. The program determines this by your CPU clock, which can be changed. If you play the game with the date set to a full moon, you'll see one of these levels denoted by a flag witrh a circle. So get out the almanac and start exploring!

Skirmish Mode:
Solved the game? Can't find a biological opponent? You can play all those multiplayer maps against the computer! Just go to your DOS prompt and start the game using '-1player' as a parameter. In the following example you should be in your Dungeon
Keeper directory:
C\>keeper95 -1player or C\>keeper -1player

Sacrificing
One of the biggest mysteries in Dungeon Keeper is what to sacrifice at the temple.
Temples also make your monsters happier, can cure them of disease or chicken-ness.
But the most fun is to drop your creatures into the temple waters to see what happens.

Here is what we've found so far:
Imps                                 Sacrifice a few of these little guys and they get much cheaper to create!
Well worth it.
Fly & Spider                         Get a Warlock
2 Beetles                            Complete current manufacturing
2 Flies                              Complete current research
Beetle & Spider                      Get a Dark Mistress
3 Spiders                            Get a Bile Demon
Ghost                                All your chickens die
Vampire                              All monsters diseased
2 Bile Demons                        All monsters turn into chickens
Horned Reaper                        All monsters angry!
Dark Mistress & Bile Demon & Troll   Get the Horned Reaper

Do NOT sacrifice the undead or chickens, unless you like making the gods angry.
Speaking of the Horned Reaper, he's a great fighter, but can go a bit bezerk at times. If he gives you too much trouble, you can pay him off by dropping money on him. Makes him happier (me too).