Aincrad · underground
Alex's Caves
Open the official mod page ↗
Click the image to open the official download & documentation page.
Deep below Aincrad are six exotic cave worlds, each one its own themed mini-realm with unique creatures, blocks and loot. They don't appear on the surface — you have to hunt them down with a map you craft from a Cave Tablet, which makes finding each one a little adventure of its own.
The six caves
| Cave | Theme | What's down there |
|---|---|---|
| Magnetic Caves (start here) | Metal & magnetism | Flying robots and magnetic fields that push or pull your iron gear. |
| Primordial Caves | Prehistoric jungle | Dinosaurs — some you can tame and ride. |
| Toxic Caves | Nuclear wasteland | Radiation, uranium, and the chunk-eating Nucleeper. |
| Abyssal Chasm | Deep ocean | A rideable submarine and the trade-or-fight Deep Ones. |
| Forlorn Hollows | Gothic / cursed | The darkest, most dangerous, late-game cave. |
| Candy Cavity | Surreal sweets | Cute candy creatures — and a few that bite. |
Notable creatures¶
There are 40+ creatures across the caves, from 2 HP minnows to 600 HP titans. Here are the headliners — you'll discover the rest as you explore.
| Creature | ❤️ Health | Threat | What makes it special |
|---|---|---|---|
| Tremorzilla | 500 | Kaiju boss | A multi-segment titan you raise in the Primordial Caves. Fires a radioactive beam that chews through terrain. |
| Hullbreaker | 400 | Boss | Giant abyssal beast that collects the loot of everything it kills and spits it back out when it dies. |
| Tremorsaurus | 150 | Apex predator | A T-Rex-style hunter whose roar shakes the screen and scatters nearby mobs. Tameable. |
| Forsaken | 250 | Hidden boss | Forlorn Hollows boss — sonic blasts and summons of darkness. |
| Nucleeper | 40 | ⚠️ Extreme | A nuclear creeper. Its blast does massive damage, flattens chunks, and leaves long-lasting radiation. Keep it far from builds. |
| Deep One | 30 | Neutral | Fish-folk you can barter with in the Abyssal Chasm — friendly or hostile depending on your reputation. |
Terrain damage
The Nucleeper and the craftable Nuclear Bomb cause chunk-eating explosions that can wreck builds. Keep them well away from shared areas and other people's bases.
Why go down there
Each cave drops materials you can't get anywhere else — uranium for bombs and reactors, magnetic neodymium for gadgets, pure darkness for late-game gear, dino meat and bone for armor, and more.