NPC spawning

Related:
* Random encounters
* Monster generator - in case the spawning can be stopped by destroying an object.
* Pop-up mooks - respawning process may appear like creatures are popping up out of nowhere, but players normally don't see it (unless they have a habit of running back and forth rapidly).
* Re-animators

See also: NPC refills where areas are repopulated by unrelated things

This is also the norm for MMOs, so tagging them is somewhat redundant, but there are cases where no AI controlled adversaries exist and some may have some form of biological simulation running that removes the need for artificial respawning, so this tag could still be used where appropriate.

Although unrealistic in most cases, this provides some extra entertainment for players when they backtrack/revisit locations they have been to earlier. No longer finding them devoid of life as they left them. Usually coupled with corpses and dropped items disappearing at similar pace.

There are two common approaches to produce NPC (re-)spawning.
* Literally respawn the creatures at their "start" locations, some have the decency of adding a teleport-in effect or similar.
* Spawn new replacements that arrive from "outside", whether they're exactly the same as the old is irrelevant.

Limitations:
* NOT for simulated breeding
* NOT for devices that spawn creatures that can be stopped indefinitely

The spawning process is usually limited to replacements, but can occur without such limit.