In most MMO RPGs (at least among the ones I've tried), monsters spawn at certain spawn points. You kill 'em, wait long enough, and they respawn. Sometimes they won't spawn if there are players nearby (which is probably intended to prevent camping out at spawn points), and in some cases the respawn may be within a certain area rather than a specific point, but the basic idea is the same. That cave over there is the Big Hairy Spider cave, and no matter how many times you kill the BHS, she's going to reappear in that cave later. This is one of the things that breaks immersion for me, and also seems like a wasted opportunity for players to have an impact on the world. Basically, killing mobs doesn't change anything about the world, as the mob is going to just come right back. So, I'd like to explore alternatives. An easy answer in a single-player game is: simply don't respawn the mobs. You kill 'em, they're gone. Of course if there isn't some means of reproduction, this would also mean a fixed amount of experience and drops in the world. But you could set up a simple ecology where the monsters reproduce, and perhaps even eat each other, leading to classic boom/bust population cycles which the player would affect by killing things (especially top predators). It also means that if you wipe out all the Big Hairy Spiders, then there aren't any more BHSes in the world, and that cave that used to be infested is now safe. (Until something else moves in... which would require an additional game dynamic: newly born monsters look for a place to make their den.) However, in an MMO, I think it'd be much harder to make this work. Early players of the game would so muck with the ecology that by the time later players join, it would be unrecognizable. Entire species of monsters would be wiped out — almost certainly including the top predators, leaving a world overrun with bugs and bunnies. So here's a novel idea: a multiplayer online game, where you and a group of your friends all start at once, and get your own instance of the world. Then me and my 12 closest friends start in a world with all sorts of scary monsters, and we can choose to wipe them out and plant wheat, or harvest carefully so as to manage the ecology, or ignore them (except in defense) and go set up shop in the mountains, or whatever. As buff heroes with lots of sharp implements, we can have a dramatic effect on the world — and that's OK, because it's our world. Basically, this is the same approach as in a single-player game, but with the social aspects of a multi-player game. And I guess, now that I think of it, that it wouldn't have to be a group of friends; you could just start a new game, say, once per month, and everybody jumps in on that world. But if it really were hundreds or thousands of players you don't know, the result would uniformly be wiping out of all the large species. So, what else can we do? What about having some unkillable reservoir of each species? It's hard to see how to do this without going right back to spawn points/zones, though. But we could take the example of locusts, who disappear underground for some prime number of years, and then reemerge all at once. Maybe big predators could do something similar: when their population is getting low, the last few individuals hide underground or in the Astral Plane or whatever, reproduce out of sight, and then reemerge later, perhaps where they hid. So, you can still clear out an area if you do it quickly, but most likely there will be some other area where some got away and will reemerge later. I don't know if that's enough to prevent the collapse of the ecosystem, but it might help. A variation on that idea is to assume that the world the players can roam in is only one part of a much larger world, and no matter how well they clear out that part, all monster species continue to thrive elsewhere. So you'd basically get monsters spawning on the borders of the territory, and wandering in (and setting up shop wherever they can find a comfy hole). This is pretty realistic. Again, in an MMO, it could spoil the fun for later players, as they'd find the starting areas almost completely empty, and have to wander for days before they run into who-knows-what. But maybe it would work, especially if you're trying to create a virtual world rather than the classic stats-based game. What do you all think? What alternatives are there to respawning monsters at designated locations?