Break Block Spawn Random Structure

Minecraft version: Java Edition 1.21.1
Type: Datapack-based Minecraft project
Main mechanic: When the player breaks a block, a random structure is generated at the broken-block location.

1. Core system

The project should include:

Detect when a player breaks a block.
Select a random structure.
Generate the selected structure at or near the broken block.
Support all normal overworld blocks as triggers.
Prevent the system from triggering repeatedly from blocks generated by the structure itself.
Work correctly in survival mode.
Support multiplayer.
Avoid excessive lag from generating too many structures.
Include a configurable cooldown.

1. Structure categories

Include a large variety of structures:

Small

Small house
Farm
Watchtower
Camp
Well
Ruined hut

Medium

Village house
Blacksmith
Tower
Temple
Fort
Mansion
Mine entrance

Large

Castle
Large village
Fortress
Giant tower
Large mansion
Underground base

Vanilla-inspired

Ruined Portal
Mineshaft
Desert Temple
Jungle Temple
Ocean Monument
Woodland Mansion
Stronghold
Ancient City
End City

1. Mob system

Structures should be populated according to their type.

Village structures

Villager
Iron Golem
Cat
Cow
Pig
Sheep
Chicken
Horse
Donkey

Castle/fortress

Zombie
Skeleton
Spider
Creeper
Witch
Pillager
Vindicator
Evoker
Ravager

Mineshaft

Cave Spider
Spider
Zombie
Skeleton
Creeper
Witch

Desert

Husk
Skeleton
Spider
Creeper
Camel
Rabbit

Snow

Stray
Wolf
Polar Bear
Goat
Skeleton
Zombie

Ocean

Drowned
Guardian
Elder Guardian
Squid
Glow Squid
Dolphin
Axolotl
Cod
Salmon
Pufferfish

Nether

Blaze
Wither Skeleton
Piglin
Piglin Brute
Zombified Piglin
Ghast
Magma Cube
Hoglin
Zoglin

End

Shulker
Enderman
Endermite

1. Rare structures

Make certain structures extremely rare and more dangerous.

Examples:

Ancient City

Warden
Skeleton
Zombie

Nether fortress

Blaze
Wither Skeleton
Piglin

End City

Shulker
Enderman

Very rare boss structure

Wither

I would not automatically spawn the Ender Dragon when breaking a block. Make boss structures extremely rare and configurable.

1. Randomness

Use different rarity levels:

Structure Rarity
Small house Very common
Farm Very common
Tower Common
Village Common
Castle Uncommon
Mansion Rare
Temple Rare
Mineshaft Rare
Ancient City Very rare
End City Very rare
Boss arena Extremely rare

1. Mob spawning

Don’t simply place mobs randomly.

The project should:

Generate the structure.
Determine the structure category.
Select appropriate mobs.
Spawn them at sensible positions inside/around the structure.
Use random quantities.

For example:

Small house: 1–3 mobs
Village: 5–15 passive mobs/villagers
Castle: 5–12 hostile mobs
Mineshaft: 3–8 hostile mobs
Ancient City: 1–3 dangerous mobs
End City: 3–8 End mobs

1. Important technical protection

The project must prevent this problem:

Structure spawns → structure contains blocks → those blocks break/change → another structure immediately spawns.

Add a structure-generation protection system so blocks generated by the datapack don’t accidentally trigger another structure.

Also include:

Player-only triggering
Cooldown
Structure spacing
Dimension checks
Mob limits
Anti-lag protection
Multiplayer support

1. Dimensions

Configure separate structure pools for:

Overworld

Villages
Houses
Castles
Temples
Mineshafts
Ancient City
Ruined Portal

Nether

Nether Fortress
Bastion-style structures
Nether houses
Lava towers

End

End City
End towers
End arenas