Differences from mcMMO

Differences from upstream mcMMO

This is a port, not a fork that tracks upstream. It targets single-player, and a large amount of mcMMO exists only to serve a multiplayer server. That part was removed rather than disabled.

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Added

Six skills upstream doesn't have, plus a restructure.

The movement group

Acrobatics was renamed Agility and turned into a child skill — it owns ten sub-skills but earns no XP of its own. Its level is the mean of three brand-new primary skills:

New skill	Trained by
Parkour	Sprinting on land (also fall/roll/dodge)
Swimming	Swimming
Flying	Elytra gliding

Six of Agility's ten sub-skills are new: Fleet Footed, Athlete, Smash, Lead Lungs, Glide, Lake Raider, Solar Wings, plus the Second Wind super ability. Full details: Movement Skills.

Stealth

Trained by sneaking. Padfoot, Assassin (backstab), Smoke Bomb super ability. Full details: Stealth.

Unarmored

Trained by taking damage with every armour slot empty. Iron Skin (real armour points at four tiers) and Thorny Skin. Full details: Unarmored.

The speed-normalised XP model

Movement and sneak XP are paid per second of travel with distance clamped at a reference speed, rather than per block. This is a genuinely new XP model, and it exists so that speed buffs aren't XP multipliers and so a movement skill can't accelerate its own levelling. Explanation.

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Changed

Combat XP is per hit, not per kill

A deliberate ruling that shifts the whole combat XP rate. A tanky mob you hit fifteen times pays fifteen times.

/mcstats <skill> replaced the per-skill commands

Legacy's /mining, /swords, /archery, … all collapsed into one command that shows strictly more: not just your ranks, but the live computed value of every sub-skill effect at your current level.

Skill data is per world

Stored in <world save>/mcmmo/players/, not in a global profile or a database. Copying a world copies its skills.

Behaviour differences worth knowing

Change	Detail
Horseback harvesting pays nothing	Prevent_AFK_Leveling is shipped on (upstream ships the key but never consults it).
A chorus tree pays for every block	The multi-block traversal now actually runs.
Sub-100 Repair destroys all enchantments	Faithful to upstream, but a harsh surprise. Get an Arcane Forging rank first.
Placed blocks are tracked across restarts	Place → quit → reopen → mine still pays nothing.
Old Acrobatics progress zeroes out	Child skills have no save key, so there's nothing to migrate to. See Movement Skills.

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Not ported

Everything multiplayer

• Parties, party chat, party teleport (/ptp), party XP sharing
• Admin chat, scoreboards, MOTD and broadcast systems
• MySQL, and all database conversion tooling
• Permission-node integrations (single-player collapses these to op level / config)

Commands

/party, /ptp, /mcchat, /mcscoreboard, /mmoedit, /mcgod, /inspect, /mctop, /mcconvert, /skillreset and the rest of the multiplayer/admin tree. See Commands for what does exist.

Features

• Chimaera Wing
• Limit Break — see below
• Spears' super ability — depends on a custom item and a spear damage type that don't exist in 1.21.11

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⚠️ Dead enums — present but doing nothing

These appear in /mcstats and in the config files, and have full rank ladders. No code reads them. They are listed here so you don't waste time levelling toward them.

The eight Limit Breaks

ArcheryLimitBreak, AxesLimitBreak, CrossbowsLimitBreak, MacesLimitBreak, SpearsLimitBreak, SwordsLimitBreak, TridentsLimitBreak, UnarmedLimitBreak.

Five unimplemented super abilities

Explosive Shot (Archery), Super Shotgun (Crossbows), and the Tridents, Maces and Spears abilities. All are registered placeholders with no behaviour.

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Blocked, not dropped

Alchemy Concoctions tier gating. The custom-ingredient tree in potions.yml loads and works, but the level gate that should restrict which tier you can brew has no seam to hook in 1.21.11 — the relevant vanilla method is static and carries no block position, so there's no way to find out whose brewing stand it is.

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Deliberately kept

Some upstream behaviour is surprising but was kept on purpose for faithfulness:

• Sub-100 Repair strips every enchantment. Harsh, faithful, flagged rather than fixed.
• A flower pot is consumed on a failed Hylian Luck roll. A legacy quirk, preserved.

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Relationship to upstream

mcMMO is GPL-3.0 and so is this. Original authors retain copyright; the contributor list is preserved in git history and on the upstream contributors page.

If you want the full multiplayer mcMMO experience, use upstream mcMMO on a Paper/Spigot server. That is what it is for, and it is actively maintained. This port exists for people who want the skill system in single-player Fabric.