Alex's Caves

Alex's Caves adds six rare underground biomes to Minecraft 1.20.1, each one a self-contained pocket of the Overworld with its own stone, plants, mobs and loot. You will not stumble into them while mining. Finding one starts with an Underground Cabin and the guide book inside it, so this cave mod is a progression to work through rather than a set of new blocks that show up on their own. It needs the Citadel library and runs on Forge and NeoForge.

How to find the cave biomes

The six biomes are deliberately rare, so the mod hands you a trail instead. Underground Cabins generate in ordinary Overworld caves, outside the new biomes, and every one of them holds a loot barrel and a Spelunkery Table. The barrel carries Cave Tablets and has a chance at the Cave Compendium, an in-game guide book that unlocks a section for each biome as you progress. Mineshaft chests and some cartographer villagers also carry maps pointing at the nearest undiscovered cabin. If you install the mod and see nothing new for a few hours of caving, that is the design working as intended.

The six cave biomes

Each biome generates as one large chamber with its own fog, light colour and ambient sound. Five of them spawn inland underground. The Abyssal Chasm is the exception and only generates under non-warm ocean biomes.

Magnetic Caves

Galena, an iron-rich stone, studded with giant neodymium crystals in two colours. Scarlet neodymium pulls metal towards it and azure neodymium pushes it away, so iron and netherite gear turns simple movement into a fight. Metal boots pay you back a little by letting you walk on the sides and underside of a scarlet neodymium block. Teletors, Magnetrons, Boundroids and Ferrouslimes hunt here, while small Notor drones scan for intruders and report them to everything else. Magnetic Factories are the loot structure. The hazard is the Tesla Bulb, which arcs lightning at anything nearby and explodes if you mine it or hit it with a projectile. Galena itself compresses into packed galena and smelts down into iron nuggets, which makes the biome a bulk iron source.

Primordial Caves

Limestone caverns lit nearly to daylight by ambersol, an amber that illuminates every block beneath it, which is why ordinary monsters do not spawn here. Pewen and ancient jungle trees, curly ferns, cycads and flytraps cover the floor, muddy lakes sit between them, and volcanoes break through the ground. The residents are dinosaurs. Grottoceratops, Relicheirus, Trilocaris and the rideable Atlatitan are neutral, the tameable Subterranodon works as a flying mount, and pack-hunting Vallumraptors and the Tremorsaurus are what will actually kill you. The Luxtructosaurus is the biome's boss. Breaking amber sometimes yields an Amber Curiosity, the key ingredient for an Amber Monolith that slowly repopulates the surrounding area with animals.

Toxic Caves

A nuclear wasteland built from radrock, a dark green irradiated stone, and the only biome where uranium ore generates. Pits of acid split the open ground, corroding your armour before dissolving whatever is wearing it, and geothermal vents bubble a deadly miasma above them. Ruined bunkers and monuments hold metal barrels of loot alongside scrap metal, copper and radon lamps, but picking up a waste drum or a uranium rod irradiates you on the spot. Nucleepers are cybernetic creepers that charge into an atomic explosion, and Brainiacs are the undead heavies. Radgills swim the acid, Gammaroaches prey on anything already irradiated, and the tameable Raycat absorbs radiation for you.

Abyssal Chasm

The one biome you cannot walk into. It generates only under non-warm oceans as a flooded trench, walls lined with abyssmarine and a floor of muck thick enough to slow you down. Tuff seamounts rise out of it carrying ores and hydrothermal vents, and whalefalls, abyssal ruins and Deep One ruins hold the loot. Deep Ones, their Knights and their Mages can be traded with and befriended, or turned against you. The Hullbreaker is the leviathan-scale predator here, a fish over fifteen blocks long with 400 health that hunts anything glowing and bites through submarines, so killing your lights is what makes it pass you by. Mussels drop pearls for an Abyssal Altar, and muck yields sea glass shards that craft into depth glass.

Forlorn Hollows

Layered canyons under a darkness thick enough that almost no light gets through. The rock is guanostone, petrified guano carrying its own redstone ore variant, and coprolith, which carries a coal ore variant and the occasional Peering Coprolith staring back at you. Lighting the place up is the trap. Torches draw clusters of Gloomoths, and Underzealot cultists sacrifice the biome's flying mobs to the Darkness. What the Darkness makes from them, the Watcher and the Forsaken, are the boss-tier fights. Corrodents ambush from underground and Vespers drop from the ceiling. Forlorn Ruins, Forlorn Idols, Forlorn Bridges and the Underzealot Borough are what you loot.

Candy Cavity

Added in version 2.0.0 and the newest of the six. The ground is stacked blocks of chocolate, frosted chocolate and cake layers, so the terrain reads like a sliced layer cake, cut through by rock candy roads and rivers of purple soda. Sundrops keep it bright, donut arches span the gaps, and licoroot trees and giant lollipops stand in for forest. Licowitch Towers and Gingerbread Towns generate here. Licowitches cast spells at you, Caniacs charge you down, Gumbeepers lob bouncing gumballs, and Caramel Cubes leave patches that glue you in place. Gum Worms, Gummy Bears and thieving Gingerbread Men are neutral, and the Candicorn tames with caramel apples into a speed mount. Chocolate crafts into hot chocolate bottles that hold off phantoms when you have skipped sleep.

How to install Alex's Caves

1. 1.Install Minecraft Forge or NeoForge for version 1.20.1.
2. 2.Download the Citadel library from Modrinth and put the jar in your mods folder. Citadel is the mod's one required dependency.
3. 3.Download Alex's Caves from Modrinth and drop it in the same mods folder. The general steps for Java mods apply here.
4. 4.Launch the game. Both jars have to load without errors before any cave biome will generate.

Version support

All thirteen releases on Modrinth target Minecraft 1.20.1, and the newest of them, version 2.0.2, went up in October 2024. There are no builds above 1.20.1 and no Fabric port. A mod compiled for 1.20.1 will not run on a newer Minecraft release, so playing this one means pinning a launcher profile to 1.20.1 instead of using your current version. The project also recommends playing without shaders, since many shader packs override the custom fog, brightness and light colour that carry each biome's atmosphere.

Multiplayer and server use

Alex's Caves must be installed on both the client and the server. The mod generates cave biomes at world creation time, so adding it to an existing world only adds new biomes in previously unloaded chunks. On an active server this means venturing into unexplored areas rather than revisiting already-generated terrain.

Pairing with Alex's Mobs

Alex's Caves comes from AlexModGuy, the same creator as Alex's Mobs, and it ships with built-in support for that mod and for Just Enough Items. Alex's Mobs spreads creature variety across the surface and ordinary caves while Alex's Caves keeps its own roster inside the six new biomes. For more worldgen alongside it, Biomes O' Plenty rewrites the surface biome set and Deeper and Darker builds out the Deep Dark and the Otherside below it. Check each one's own loader and version support before stacking them.

Alex's Caves Mod Showcase for Minecraft 1.20.1

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