MobRules

What MobRules Does

MobRules is a lightweight mod for Minecraft 1.21.1 that provides comprehensive and granular control over mob spawning through three distinct categories:

Hostile Mobs: All aggressive creatures including monsters, undead, and other threats
Farm Animals: Domestic and passive land animals typically used for resources or companionship
Aquatic Animals: All water-dwelling creatures from fish to amphibians

Each category offers three levels of control:

Allow All (false): Normal vanilla spawning behavior
Block All (true): Completely prevent spawning for the entire category
Selective Control (partial): Use customizable JSON allowlists to specify exactly which mobs can spawn

Advanced Configuration

When using "partial" mode, MobRules generates JSON allowlist files in your config/mobrules/ directory:

hostile_mobs_allowlist.json - Controls which hostile mobs can spawn
farm_animals_allowlist.json - Controls which farm animals can spawn
aquatic_animals_allowlist.json - Controls which aquatic animals can spawn

These files are automatically created with sensible defaults and can be edited to include only the specific mob IDs you want to allow. For example:

[
  "minecraft:zombie",
  "minecraft:skeleton",
  "minecraft:creeper"
]

Why MobRules Exists

Every Minecraft player has encountered situations where default spawning mechanics don't align with their goals:

Creative builders who want inspiration from a living world without combat interruptions
Server administrators managing performance with selective mob populations or creating themed areas
Modpack creators needing precise control over which creatures populate their custom worlds
Accessibility-focused players who want to reduce specific stressors while maintaining gameplay
Role-playing servers requiring specific atmospheric conditions with custom creature populations
Adventure map makers who need exact control over which mobs appear in different areas

MobRules bridges the gap between Minecraft's default spawning and the diverse needs of its community, offering everything from simple on/off switches to precise per-mob control through easy-to-edit configuration files.