I hope we can all agree that the Dungeon Keeper games are about building a good dungeon, which attracts evil creatures, which in turn will help you improve your dungeon further to attract more creatures and kill of the goodly heroes trying to destroy you.
However, in DK1 if you build a treasure room, a lair and a hatchery, 3 rooms you'd need anyway you immediately attract Dragons and Bile demons, which are two of the most powerful creatures in the game. If beetles, flies or demon spawn creatures decide to walk into your dungeon you are crazy if you don't kick them out to make room for the stronger creatures. If you wait a little while you can build a training room to get dark mistresses in your dungeon, perhaps barracks for Orcs and you'll have all the creatures you'd even want. In other words getting the creatures you want is accomplished by kicking out weak creatures until only strong creatures remain, not by making tactical choices or building exceptional dungeons. DK2 is even worse, in this game you only want black knights, so build a combat pit as soon and large as possible to win the game.
OD has introduced a tiered system to try and address some of the issues in those games, where high tiered creatures are dependent on which lower tiered creatures you have. Still, the overall concept remains the same: build all rooms and creatures will stream in, kill creatures you don't want. In truth, this is not very engaging. To share my personal experience, when I played this game for the first time I received dragons and pit demons which are the strongest creatures I could get, and I didn't even know what I did to deserve that. At this point I'm still wondering if because the game is in alpha state you get all creatures all the time to test them, or if I accidentally met the criteria to draw them in.
However, getting powerful creatures should feel like an accomplishment, not an inevitability. I therefore want to propose a better system: Make high tier creatures be acquired through the use of your dungeon.
We want the backbone of the game to be: Dungeon -> Creatures -> Better dungeon -> Better creatures -> Better dungeon -> Better creatures -> ...
To elaborate on this, when you start out you can build a simple dungeon which can only attract better creatures. These basic creatures should use your dungeon to allow you to improve your dungeon. Use is the key word here, and on the first tier this is for example using the library to research new rooms. Those advanced rooms may attract new more powerful creatures to your dungeon. (So far this is the current scenario.) However, all further improvements to the dungeon and creatures should come from creatures working the available rooms somehow. In DK the prison, torture chamber and graveyard are already rooms that can be used to get new creatures, and not surprisingly they are the most popular rooms. These are all very nice, but all based on converting enemies so I feel it would be nice to introduce some mechanics where rooms/creatures are used to get higher tiered creatures without capturing/killing enemies. The specifics are to be elaborated and ideas are welcome, but to give some examples:
- * Cultists could use an altar room to summon a powerful demon directly from hell
* A mad scientist would be able to kill several creatures in his lab to create his 'Frankenstein's Monster'
* A troll could use his workshop to build 'golem' type creatures if provided the right ingredients from the map. Collecting lava could build you a lava golem or something.
* A small fighter unit could turn into a powerful fighting champion type by training beyond the max. (Think demon spawn -> dragon in DK1, just don’t make the latter creature available directly.)
This all sounds a bit ambitious, and if this goes too far you could think of simpler methods making acquiring high level creatures more of an accomplishment. This could be that high tier units need the late game rooms to be attracted and those can only be researched when specific criteria are met, so that receiving them is not automatic.