So far in the realism poll the most votes cast are for a segregated fantasy, with the second most votes for full on fantasy. Along that vein I had a thought. First off caves and the beast type creatures occupying them. It could be set up such that they'd keep mostly to the caves (with maybe a random spawn occasionally in the area of the cave, that in itself if you come across a random spawn while exploring it could act as a signal there's a cave with that type of creature nearby,) but left unraided for a while the spawns would slowly start to creep out of the cave ultimately reaching a fixed max radius around the entrance. Also dungeon type creatures. There could be an element where in certain specific regions of the world there's a possibility for a random event of say, a band of orcs to start wandering around raiding. Or a necromancer to raze an army of the dead, build a small castle and maybe a couple outposts off of their labor and start attempting to destroy nearby settlements. The idea here being that there are certain safe regions of the world, where if you don't want to have to worry about the fantasy elements coming in and wrecking your settlement you can have that. But if you want to go build in more dangerous territory because you'd find it exciting you can do that as well. In the case of NPC settlements you could even use them as a way for people to get a feel for the safety of the region. In a relatively safe area there may just be a small town with some farms and no defenses. In a more dangerous region any settlement would be walled off and protected by armed guards. The more defenses the more dangerous the region. This way there's areas of the world for everyone regardless of preference and the fantasy doesn't feel disconnectedly trapped underground. Edit: (Apologies in advance for the word vomit here.) Also for the beast type creatures in caves you could have a max spawn radius attached to the mechanism that allows them to overflow. So in a dangerous area some (for the sake of example) giant venomous spiders could completely overtake a swamp if left for too long, but in a safer area a couple cougars would end up at the cave entrance. In practice you'd have the current spawn radius, starting at 0 and gradually increasing the longer the cave has gone without being wiped, up to a max spawn radius unique to the individual spawner attached to the cave, with a density variable determining the number of spawns that could occur per unit of space within the current radius (occuring randomly throughout the radius using the same detection mechanism for where and where not to let them spawn as you use for deciding where you can and cannot teleport) wiping each individual spawn on creature death and generating a new one at whatever random time interval they spawn at already, spawning new ones as the radius increases. Decrease in the radius could drop gradually proportional to the percentage of creatures total that have been killed, so if it's at a max radius of 10, and the number of spawns inside the cave plus the number of allowed spawns given the radius and density was somehow conveniently 100, and you kill 10 creatures, the current spawn radius drops to 9 and so on, down to a full wipe that sets the radius back to 0. That's just my two cents anyway, I don't know how the community would feel about that, and I don't know what the current big picture plans are and how that would or wouldn't mesh with them, or even how difficult it would be to code all of that in practice. In any case I had the thought so I figured I'd throw it out there.