Something fell from the sky. It is still growing.

Core Ecosystem is a living alien colony for Minecraft. It lands as a meteor, takes root, and builds a world of its own out of yours.

It takes root. In the crater sits the Core. Its creatures bring it food, and the more it is fed, the more it grows. It grows in nine phases, and it does not need you there. Walk away, and when you come back the ground has changed. The last phase is not on this page.

It builds a colony. Gardeners feed the Core. Guards defend it. Worms eat the ground and leave Infested Ground behind. Sun Collectors drink the daylight so the Core can digest. It grew every one of them.

It is watching. Its creatures are its eyes. Whatever they can see, the colony can go after. Hurt one of them, or break one of its living veins, and it holds you as an attacker.

Later, it breathes. What it breathes out is an infection.

It can be fought, and it can be stopped. Find it early, or it finds you.

Good to know

• Minecraft 1.21.1 with NeoForge 21.1. Goes on the server and on every player's game. No backports for now.
• No pop-up text and no narrator. The world shows you what is happening: sounds, light, your own body.
• Hundreds of settings, in plain words.
• Works with Jade, Spark, WorldEdit and Fungal Infection: Spore.
• In active development.

Making videos?

• Spawn eggs for every creature.
• A creative-only Colony Lens that tells you what the colony is doing.
• One command, /core_eco, to spawn a colony and jump it to any phase.
• The colony keeps growing with nobody near, so a time-lapse shows it spread.

Heres some more useful information about the actual contents of my mod:

The first days

• The pod. Half a minute after you first join, a small scorched pod drops near you. Inside are a note, What Fell Here, and the RVI Tablet. Keep the tablet: it has no recipe.
• The RVI Tablet is your compass to the Core Tree (it replaced the Core Locator). Sneak and use it to see the phase on its dial. Use it to wear its goggle view: the distance to the Core, and a Log of the notes you find.
• The meteor comes within your first five days, on dry land up to 550 blocks from a player. You feel it from 350 blocks away, and its blast throws everything within 48 blocks. In the crater sits the Core Tree.
• The escape pod crashes at dawn on the third day after, 400 to 900 blocks from the Core. Its dead crew left three logs on its Log Screen. Scan the screen through the goggles, and from then on a thrall you look at shows how long it has left.

How it lives

• Biomass is its food. Its creatures gather living matter, cut its grove, and tie up animals, villagers and hostile mobs to carry home. Every block its veins and worms take feeds it a little.
• It digests. Only digested biomass can be spent. SubCore Trees and joined Ascended Trees speed that up, and its Sun Collectors most of all: leaf plants it grows on its veins under open sky (Small and Medium from Phase 3, Large from Phase 8). They open by day, fold at night, and work best at noon.
• Its land. Veins spread in arms, and worms eat the ground between them. Each block keeps the look of what it was: Overgrown Grass, Rooted Stone, Veined Sand. Living veins are damp, so fire goes out on them. Cut off, they go grey, and grey veins burn. Once it is well fed, its creatures heal on its land.
• It takes its time. No phase ends before 8 minutes with one player online; a minute less for each player more, two less with Spore installed. It keeps its land loaded and grows with nobody near. A chest left on its land is emptied.

The nine phases

1. Rooting. Roots spread out of the crater. Two Gardeners, a Brute Guard and a Scout Guard climb out, and a Seedpod Launcher sits on the Core.
2. Budding. A shell of black bark grows over the Core. More Gardeners and a second Brute come.
3. Awakening. The shell closes, lit inside by Glow Pods. A Grafting Root grows beside the Core. The Gardeners plant a grove of Core Saplings and feed the grown trees back to the Core. The Core grafts a stronger arm onto each Gardener in turn. The first worm and the first Sun Collectors appear.
4. Revelation. A taproot digs down, and arms of veins reach across the land, lit by Glow Pods. Ore they touch becomes veins. More Gardeners and Guards come.
5. Hatching. The egg cracks and a heart beats inside. The Guards grow to at least 20 Brutes and 12 Scouts and patrol in parties. A Gardener carries a SubCore egg far out onto the land.
6. Spreading. The SubCore Sapling stands, joined to the Core by an underground cord, with two guards of its own; a second follows. Each lets out three Mites, once, and the first Ascended Trees grow where their victims fall.
7. Seeding. Two more SubCores. Every joined Ascended Tree breathes the Miasma. With 15 trees and 15,000 biomass, the SubCores grow into tall SubCore Trees, the heart's health doubles, and mist hangs round the Core. Dragonflies and SubCore Vines come out of the new trees.
8. Guardians. At 25 joined Ascended Trees, sacs grow inside the shell and giant spiders climb out. Wrapping Vines come up round the dome. In the Miasma you feel fed, and animals are drawn in. A root digs down to bedrock.
9. Rising. With 20,000 biomass, two grown Guardians, 40 joined trees and two days in Phase 8, the shell swells into a bulb, and the Core rises into its middle inside a beating heart of flesh. A stalk climbs up to 200 blocks, a closed bud on top. Then, for three minutes, everything near it goes silent: its creatures freeze, the vines lie flat, the animals run. Then it opens. What opens, and what comes up out of the veins with it, is not on this page.

Its creatures

• Gardeners gather, feed the Core, tend its grove, carry prey home and put out fires on its veins.
• Brute Guards fight hand to hand; Scout Guards shoot and lead the patrols. Both walk across water. Seedpod Launchers sit on the Core and fire bursting pods.
• Worms eat the ground into Infested Ground: one in Phase 3, one more each phase after. Now and then one dives up to 10 blocks down, and when its rounds are done it eats the plain patches left inside the land.
• Dragonflies scout high over the land, catch small animals, and carry Mites to far animals and thralls to far trees. They never attack players.
• Wrapping Vines whip you in, wrap you up and squeeze; hit from inside to break free. Each keeps 16 blocks from the next, goes where the most mobs are, and grows tougher with every kill.
• Carnivorous Flowers are grown vines reborn from a chrysalis. Hidden in the ground, they bite within 4 blocks and shoot hostile mobs.
• SubCore Vines stand in pairs by each SubCore Tree, twice as tall: they shoot from 20 blocks, blind what they hold, and let go only after 10 hearts of damage.
• Fire hurts Wrapping Vines and SubCore Vines twice as much.

When it comes for you

• Its creatures are its eyes. It goes only after what they can see. Out of their sight for 5 seconds, you are lost to them.
• In Phases 1 and 2 its Guards attack anyone within 24 blocks of the Core. From Phase 3 they wait until you attack. Its vines, Guardians, Mites and mist never wait.
• You become its attacker if you hurt its creatures, mine its shell, its Core, a SubCore's egg or its Sun Collectors, or break its living veins: 3 veins bring the creatures near you for two minutes, 20 the whole colony until you die. A blast you set off counts as your own hand.
• Its shell is as soft as dirt in Phases 2 and 3, stone in 4 and 5, deepslate in 6 and 7, obsidian from 8. Dig it with a pickaxe; the obsidian takes a diamond one, and no blast breaks it. Broken blocks grow back in half a minute.
• At night twice as many monsters spawn on its ground. A torch still keeps them off.

The Miasma

• Mites. Each picks one mob or player and lives 90 seconds. It flutters at its target's head for one second before it burrows in: swat it then. Inside, it does 100 damage over 12 seconds, through any armor. Milk does nothing.
• Ascended Trees. What a Mite kills becomes a tree grown round the body, which still shows in the trunk. A player's tree keeps their name. Each creeps a trail of veins back to the colony and sends worms into the ground. Felled, it drops what its mob would have dropped.
• The mist. From Phase 7 every joined tree breathes pale seeds, and the land round it becomes the Miasma biome: olive grass, murky water, a brown sky, thick fog. In rain the mist sinks to the ground.
• The Core Must Grow. Five seconds in the seeds and they take hold. For 30 seconds you only hear a heartbeat, faster the nearer the Core. Then it takes 1 health a second, through any armor, and staying in the mist adds time. Milk does not touch it.
• Thralls. A mob that dies of it gets up as a thrall, mottled green and purple. It attacks anything not of the colony, walks away from the Core, and 2.5 minutes later becomes a tree; killed sooner, it becomes one at once. What a thrall kills becomes a thrall. From Phase 7, 15 in 100 of the mobs carried to the Core come back out as thralls. Run 400 blocks from a colony that has seen you, and thralls, sick animals or a dragonfly with a Mite may follow.
• The madness. A player who dies of it does not die: they go mad. Within 32 blocks of the Core you are hurt, more the closer you get, and your screen pulses with your heartbeat. Once a second your arm swings by itself at anything near you, and you can harm nothing of the colony's but the Core itself. Milk hides the signs, not the end: in 2.5 minutes you become an Ascended Tree, and what you kill before then gets up as a thrall.
• Spoiled meat. Raw meat from a felled Ascended Tree carries the seeds and looks like any other. Cook it. Eaten raw, one bite in three makes you sick: drink milk within the minute, or the seeds take hold twice as hard.
• The Gas Mask (five black wool, two sponges, an iron ingot) keeps the seeds and the Mites out. Its filter wears only in the Miasma or a Spore cloud: 14 in-game days (28 with Spore installed), and 3 days for each Mite it stops. Refill it with two filters; a sponge makes four. Spore's own mask works too.

The Guardians

Each starts as a veined sac inside the shell. It swells and splits, and a young Guardian climbs out and feeds until it is grown. Break the sac first and it is never born. The higher its rank, the more armor it wears.

• Hunting Guardian, an orb weaver. It sits unseen on a faint web and strings Sap Webs round the Core. A Sap Web holds you, halves your hits and calls it home. Its bite carries Acidic Sap; milk halves that.
• Cave Guardian, a trapdoor spider. It lives in a cave or a lair near the Core and hides its pit under a silk lid. It digs only to make its home, never to reach you. Its bite throws you back.
• Tree Guardian, a wolf spider. It roams the Ascended Trees and spits sap that heals the colony.
• Heart Guardian, a tarantula. It guards the heart, its bite stuns, and it wears the most armor the game allows.

A Guardian fights you down to a fifth of your health, then drags you home. Deal it 15 damage on the way and it lets go. Dragged all the way, you are cocooned in 5 seconds, and no armor or Totem saves you: only someone killing it in time. Many of its creatures dying in one place call the Guardians there. A fallen Guardian sinks into the ground, and two Gardeners who reach it within half a minute revive it.

What you can take from it (new in 1.9.10)

• Its blocks. Mined by hand, each infested block drops itself (the rock kinds need a pickaxe), and you can place them. Breaking living veins still angers it.
• The Core Harvester (two iron blocks, a flint, two sticks, four infested blocks) digs like an iron axe. Mend it with flint in an anvil, or fit a Flint Toolhead (a flint in eight iron nuggets) for a diamond pickaxe's durability for good. It holds 8 items and has a food slot. Fed (a bread lasts 2.5 minutes), it keeps what it holds fresh; starved, everything inside dies.
• Blood Resin and Strangle Vines. Fell an Ascended Tree with a fed Harvester's last hit and they may drop straight into it. Felled any other way, they turn to Dried Resin and Dead Vines in a second. Out of a fed container, a fresh one lasts 10 seconds in your inventory and one second anywhere else.
• The BioMechanical Crafter (four logs, four infested blocks, a Core Shell block: mine the shell with the phase's pickaxe, wooden in Phase 3, stone in 4, iron from 5, or with the Core Harvester). Put your Harvester and some food in its slots, and it crafts with the Harvester's fresh resin and vines.
• The Altered Bio-Sword (any sword, three Strangle Vines, two Blood Resin). It hits for 1 more than its sword, plus 0.1 a kill, up to 4 more, and every kill mends it. Each kill has a small, growing chance to get up for the nearest Core: a mob as a thrall, a player mad.
• Altered Armor (any armor piece, six vines, two resin; grown in the Crafter over 2 minutes). It protects as its piece did, and every kill mends it. But a kill made while all of it is at full durability can set it strangling you, 1 in 10 at first and more each time. Then it will not come off, and in 30 seconds you die into a tree. Get free by catching fire, by three hits from anyone's sword or axe, or by breaking a piece. A full set left on the ground becomes a tree when it would despawn.
• The Incubation Chest (a chest and a furnace in seven infested blocks): 27 slots and a food slot. While fed, the resin and vines inside stay fresh.
• Sun Collectors can be mined: a stone axe for the Small and Medium, an iron axe for the larger ones. One you place is yours: it feeds no Core, and a tendril links it to every Crafter and Incubation Chest within 8 blocks. Linked, their food lasts four times as long, and armor grows in one minute.
• The Subterranean Sonic Emitter (four cobblestone, two redstone, a plank, two note blocks) thumps every 2 seconds, and at each thump every worm within 16 blocks turns away. Set it on the colony's ground and the colony comes for you, and a Gardener breaks it.