CurseForge · Minecraft mod
Micro Mayhem
Adds simplified microbiology to minecraft with mutation and selection for traits all with both custom and vanilla effects ranging from pathogens, to neutral, to beneficial.
Quick answer
Which Micro Mayhem release should I use?
Micro Mayhem micromayhem-1.21.1-2.5.5.jar targets 1.21.1 with NeoForge. The project page does not say whether this file belongs on the client, dedicated server, or both. No extra mods listed for this file.
Where it goes
Is Micro Mayhem required on the client, server, or both?
The project page does not say whether this file belongs on the client, dedicated server, or both.
The source does not explicitly classify this release as client-only or server-only.
What else does Micro Mayhem micromayhem-1.21.1-2.5.5.jar need?
micromayhem-1.21.1-2.5.5.jar. Change the file and its required mods may change too.
This file does not list any required mods. Do not add a library just because a different file uses it.
This file does not list any required or optional mods.
Before you install it
Add Micro Mayhem without breaking your instance.
Built for Micro Mayhem micromayhem-1.21.1-2.5.5.jar. Pick another file and the loader, install side or required mods may change.
- 01
Stick to this file
Use micromayhem-1.21.1-2.5.5.jar. It targets 1.21.1 with NeoForge; another release may have different loader, side or dependency requirements.
- 02
Bring the mods it needs
This file does not list any required mods. Do not add a library just because a different file uses it.
- 03
Put it on the correct side
The project page does not say whether this file belongs on the client, dedicated server, or both.
- 04
Pick the file you checked
Use the “Get this file” button beside micromayhem-1.21.1-2.5.5.jar. It opens that exact file at the source.
About this project
What does Micro Mayhem add?
HIGHLY WIP let me know if anything breaks or if you want features mostly focusing on the 1.21.1 version for now in terms of updates to the mod I might eventually update the 26.1.2 port:
Every world in Micro Mayhem has a microscopic ecosystem running underneath it. Bacteria, viruses, fungi, and parasites live on blocks, in water, in the air, on mobs, and inside the player. You cannot see them without tools. They do not wait for you to find them.
Each organism is procedurally generated from the world seed. No two worlds have the same strains. They mutate over time, compete with each other for territory inside hosts, form symbiotic relationships, respond to biome conditions, and evolve under pressure. A commensal strain you find on day one might be something entirely different by day thirty.
You interact with this system through a set of lab tools. Swabs collect samples from any surface, mob, or the air. Petri dishes culture what you find. A microscope reads out the full biological profile of whatever you are looking at. A centrifuge isolates individual strains from mixed samples. An irradiator accelerates mutation and lets you apply directional pressure toward specific traits. A gene splicer combines two strains into recombinant offspring, sometimes producing traits neither parent had.
Infections are modeled across four body systems: respiratory, digestive, skin, and circulatory. Each has its own colony space, local immunity, and health pool. Infections progress through five stages. Severe infections cause permanent damage. A neglected circulatory infection can kill you. A healthy microbiome of established beneficial strains resists pathogens before they ever take hold.
Every world contains one unique catastrophic strain. It is out there. Finding and characterising it is the closest thing the mod has to an endgame.
Tools also exist to protect yourself. A hazmat suit blocks all environmental transmission. Antibiotics, antivirals, antifungals, and antiparasitic drugs clear infections by type. Vaccines can be engineered from cultured strains. The suit has to be sterilized before you take it off, or whatever it absorbed comes with you.
This is a beta. The systems are functional and the simulation runs. Expect rough edges.
Micro Mayhem - Basic Usage
SAMPLING
Right-click a block surface with a Swab to collect a surface sample.
Right-click in open air to collect an airborne sample.
Right-click near a mob (within 3 blocks) to sample it.
One swab is consumed per sample. The rest of your stack stays sterile.
VIEWING
Hold a contaminated Swab or ready Petri Dish and right-click the Microscope.
Results appear in chat. First view adds the strain to your Codex.
CULTURING
Hold an empty Petri Dish with a contaminated Swab in your off-hand and right-click.
Culturing takes 20 seconds. Keep the dish in your inventory while it incubates.
COPYING A CULTURE
Hold a ready Petri Dish in main hand, empty dish in off-hand, Nutrient Agar in inventory.
Right-click to copy. One Nutrient Agar consumed.
CENTRIFUGE
Place the contaminated petri dish and two empty ones in the slots and it will produce separated samples.
IRRADIATOR
Put glowstone dust as fuel.
Optionally add a pressure item to bias mutation direction.
Finally add the contaminated petri dish and empty petri dishes.
DIRECTED EVOLUTION (IRRADIATOR)
The Irradiator lets you push mutations toward specific traits by placing a pressure item in the bias slot alongside your culture.
Load a ready Petri Dish, then glowstone dust as fuel, then optionally a pressure item.
The cycle produces 4 mutant candidates. Pick the one you want. Autoclave the rest. Make copies with Nutrient Agar before irradiating so you never lose a good strain.
Pressure items and what they select for:
Blaze Rod Push toward Grade III virulence
Feather Reduce toward Grade I virulence
Sugar Bias toward beneficial effects
Rotten Flesh Bias toward harmful effects
Slime Ball Increase transmissibility
Chorus Fruit Add a new spread vector
Fermented Spider Eye Force wither/necrotic expression
Golden Apple Force regeneration/healing expression
Bone Meal Push toward commensal (no effect)
Amethyst Shard Stabilise the strain (slow future mutation rate)
Each pressure item applies with 80% probability per candidate. With no pressure item loaded the mutation is entirely random. Cycle duration scales with how genetically stable the strain is — freshly mutated unstable strains process faster than old established ones.
GENE SPLICER
Place the contaminated petri dish A and B in the slots, as well as fill the other slots with empty petri dishes.
SYRINGE
Hold syringe with a ready dish in off-hand and right-click to load.
Right-click a mob or player to inject. Right-click air to inject yourself.
Symptoms appear after a latent period, not instantly.
AUTOCLAVE
Right-click holding a swab or petri dish to sterilize it.
Right click with empty hand to sterilize hazmat suit
HAZMAT SUIT
Wear all four pieces to block all environmental and contact transmission.
Sterilize by right clicking autoclave empty handed to clean the suit before taking it off gives you 10 second grace period before it gets dirty again.
Contaminated pieces in your inventory will expose you if you are not wearing the full suit.
COMMANDS
/microbiome See your active infections and body system health.
/immune See immune strength and autoimmune status.
/codex list Browse all discovered strains.
/straininfo <id> Full details on any strain by ID.
/codex Shows total number of strains discovered in your Codex.
Project description from CurseForge.
Pick your setup
Micro Mayhem by Minecraft version and loader
Choose the version and loader you play, then open the matching release.
1.21.1
1 loader buildCheck the dependencies, then try the file in a copied instance before changing a world you care about.
Recent files
Micro Mayhem versions and loaders
micromayhem-1.21.1-2.5.5.jar
micromayhem-2.5.5.jar
7 May 2026
micromayhem-26.1.2-1.0.1.jar
micromayhem-1.0.1.jar
6 May 2026
Looking for an older file? The official CurseForge project page is in Resources.