LethalBreed

Build the wall. They will stack blocks under their own feet and step over the top of it.

You know how the night goes. A wall on day three, a roof, a door, and nothing in the game asks anything of you for the next four hundred nights. These zombies place a block, stand on it, place the next, and climb up to 24 blocks that way. The pillar they leave behind crumbles thirty seconds later, which tells you it was never about the wall.

🧱 What your wall actually buys

Nothing here walks through stone. Everything eats it. A zombie standing against a block adds 0.04 points of progress per tick, divided by that block's hardness, and the block drops at 1.0. Stone holds for 1.9 seconds.

Past a hardness of 30 they refuse the block outright. Obsidian holds, and now you have something to do with your evenings.

They do not queue up, either. One about to start digging looks for a neighbour already working nearby on something that would serve it too, and joins that one instead. The breach opens where the crowd is.

🪜 Over, under, around

• Digging under, bridging a gap and swimming are all open to them. A moat is a detour, and in deep water they climb on each other to get out.
• The break height comes from the body, one to four blocks, so a bigger specimen opens a bigger hole.
• Break line of sight and they head for the last place they had you. A noise anywhere near writes them a new one.
• Chests, furnaces, beds and spawners are left standing. They take your wall apart, not your storage.

🌞 The sun stops saving you at tier 5

A phase counter starts with the world and climbs on the world's own age, one tier every thirty minutes of it, give or take three. It ignores the day cycle, it survives restarts, and it never falls back. /lethalphase says where you are.

Tier 5 is where daylight stops burning them. From there the morning is a change in the light and nothing else.

They carry no gear at any tier. The escalation is all statistics and potion effects, bending onto a ceiling they approach without reaching, which is why tier 30, tier 50 and tier 100 still feel different from one another.

🧟 Eight of them are not normal

The odds of a specimen drawing a variant climb with the phase, up to 35% of them. No name floats overhead, so you find out by what it does.

• Sprinter, permanently quicker than the rest
• Leaper, clearing ground a body that size should not
• Screamer, pulling every idle zombie within 24 blocks onto you
• Healer, putting the wounded ones back on their feet
• Juggernaut, twice the health, and bigger wherever the ceiling lets it stand
• Necromancer, calling in more
• Splitter, becoming two when it dies
• Bomber, which never has to touch you

The Bomber stops three blocks short, freezes, and swells for anywhere from one and a half to six seconds. That pause is your window and it is the whole of it. A longer fuse means a stronger blast and filth thrown further. It breaks nothing: the walls come through it, you are the only target it has. Its ring of filth carries half again as far as the blast, so stepping clear of the lethal radius saves hit points and infects you anyway.

🦠 The plague you cannot see

Super Contamination gives you nothing to read while it is latent. No icon, no damage, no sign. The one clue is half a second of slowdown at the moment it takes.

Then it waits. Every five to ten in-game days it rolls once, with a small chance of turning, so a carrier usually goes hundreds of days before the first symptom, and then it arrives in five worsening stages.

Three of its four routes need no blow at all: a Bomber's filth, the pool that filth leaves behind, and a potion brewed from rotten flesh. Armour has no bearing on any of them. Milk takes the icon away and hands it straight back.

A villager who dies carrying it gets up again on the other side.

🔧 Built for the crowd

The pathfinding is a distance field recomputed every ten ticks on its own pool, off the server thread, over a grid bounded to 192 blocks. The tick scheduler is built around a thousand active zombies at once.

Where an OpenCL device exists the field goes to it, and JOCL travels inside the jar, so nothing gets installed on the host. No device, or a device that errors, and it drops to a multi-core solver that returns the same paths. A headless server without a graphics card plays the same game, on more cores.

The simulation runs server side and nothing is pushed to a client on join. The client half is optional and carries the contamination overlay, the hallucinations and the settings screen. /lethalconfig opens those, operators only.

🛑 Before you install

Any mod that alters zombie AI will stop this one from launching.

It drives that AI itself, so the two cannot share it. Caught at startup, the game does not launch. Caught mid-session, the server stops cleanly and your world is saved. Everything that leaves zombie AI alone is fine, performance mods included.

Modpacks are welcome, and so are forks and addons, with nothing to ask for first. A mention is welcome too, never required.

Every mechanic, every value and every command, in French and English, with a breach calculator that runs the server's own arithmetic:

LethalBreed

Zombies that climb your wall, dig under it, and get worse every night.

Required on the server, optional on the client.

Before you install

Any mod that alters zombie AI will stop this one from launching. It drives that AI itself. If one turns up mid-game the server stops cleanly and your world is saved. Everything else is fine, performance mods included.

They get over your wall

• One places a block, stands on it, places the next, and climbs up to 24 blocks that way. The column cracks apart about thirty seconds later.
• Digging under, bridging a gap and swimming are all open to them, so a wall only buys time.
• A bigger zombie carves a bigger hole, breaking whatever it has to break to fit through.
• Break line of sight and they walk to where they last heard you. Move, or be found.

Every night is worse than the last

A difficulty counter climbs on its own, server-wide, and never goes back down. There is no cap, and tier 30, 50 and 100 are still different from each other.

They carry no gear. It is all stats and potion effects, so what you meet is tougher every night you survive. /lethalphase tells you where you are.

The plague you cannot see

Super Contamination has no bar and no icon. It sits in you for 5 to 10 in-game days before anything shows at all.

You can catch it without ever being hit: a Bomber's filth, the pool that filth leaves on the ground, or a potion brewed from rotten flesh. Armour does not help.

Milk does not cure it.

Eight of them are not normal

Up to 35% of spawns carry a variant, each unlocking at a set tier.

• Sprinter (t2) runs faster than the rest, permanently
• Leaper (t3) jumps like nothing that size should
• Bomber (t4) never has to touch you
• Screamer (t5) pulls every idle zombie within 24 blocks onto you
• Healer (t6) keeps the ones around it standing
• Juggernaut (t6) is bigger and much harder to put down
• Necromancer (t9) calls in more
• Splitter (t11) becomes two when it dies

The Bomber is the one that kills you. It stops three blocks short, freezes, and swells for one and a half to six seconds. That pause is your window to leave. Its filth ring reaches further than the blast, so clearing the lethal radius saves your health and infects you anyway.

Running it

It runs server side. The client half is optional and adds the contamination overlay, the hallucinations and the settings screen. /lethalconfig opens those, operators only.

MIT. Play it, pass it on, put it in a modpack, fork it, build an addon on it, no permission to ask for any of it. Keeping the copyright notice with a copy of the code is the whole condition. A mention is welcome, never required.

Every mechanic, every value and every command, in French and English: lethalbreed.pages.dev