The Modsmith Guide
Modding is how half of today's game developers got started, and most studios welcome it. There are a few lines you must not cross. This guide covers all of them in plain language.
A mod is a set of files you add to a game to change it: a new sword, a new recipe, a chest with more space. You don't need to be a programmer. Most first mods are a few changed numbers and words.
Mods from the studio only add files to your game's folders. To undo one, delete the file you added. Back up worlds and saves before trying any mod, just in case.
No. The first lessons only change numbers and words. You'll write your first line of code a few minutes in, with a hint beside you.
Not for single-player mods like these. The risk is cheating in online games. See Multiplayer and anti-cheat.
Modsmith is free, and so are the mod loaders it uses. You just need to own the game.
Every studio has Reset to starter template. Your project saves as you type, and Undo works in the editor and the pixel editor.
Not with these studios. Console versions don't allow custom files. Minecraft Bedrock has its own add-on system that isn't supported yet.
Share what you made. Never share what the game made.
Your code, your textures, your sounds and your JSON are yours. The game's own files (its executable, its textures, its music, its models) belong to the studio, even if they're sitting on your hard drive. A legal mod tells the game to do something new using your own content, and refers to the game's content by name instead of copying it.
That's why a Factorio mod can say "copy the iron chest prototype and make it bigger" without including a single iron chest image, and why a Minecraft resource pack should contain only textures you drew yourself.
Search it for "mod", "modification", "user content" and "commercial". Five minutes tells you what the studio allows.
Data packs, tModLoader, SMAPI, the Factorio mod API, the GMod Lua API, the Creation Kit. If the studio built or endorsed it, you're on solid ground.
Draw it, record it, or take it from a source with a clear license. Keep a CREDITS.txt listing where each asset came from.
Built on someone's library or learned from their code? Credit them, and follow their mod's license.
No game textures, models, music, maps or executables in your download, even modified ones. Patch or reference them instead.
Mods that crack, unlock paid content or bypass purchase checks are illegal in most countries, whatever the EULA says.
Porting a character model from one game into another is copyright infringement. It's the most common reason mods get taken down.
Aimbots, wallhacks and mods that give an advantage in competitive multiplayer get accounts banned and can break the terms of service.
Many games forbid selling mods or locking features behind payment. Some allow donations or official marketplaces. Read the commercial-use rules first.
Calling your mod "Official Minecraft Update" implies endorsement. Use descriptive names like "Better Arrows for Minecraft".
Every asset you didn't make needs a license that lets you use it. These are the ones you'll meet in the Asset Vault and around the web.
| License | Use in a free mod? | Use in a paid project? | What you must do |
|---|---|---|---|
| CC0 / Public Domain | Yes | Yes | Nothing. Crediting is still a nice habit. |
| CC BY | Yes | Yes | Credit the author, link the license, say if you changed it. |
| CC BY-SA | Yes | Yes | Credit the author, and release your edited version of that asset under CC BY-SA too. |
| CC BY-NC | Yes | No | Credit the author. No selling, paywalls, or ads tied to it. |
| CC BY-ND | Only unchanged | Only unchanged | Credit the author and don't modify it. Rarely useful for mods. |
| MIT / Apache / BSD (code) | Yes | Yes | Keep the license text and copyright notice with the code. |
| GPL / LGPL (code) | Yes | Yes, with conditions | Share your source under the same license when you distribute it. |
| "Free to use", no license | Risky | No | Ask the creator in writing, or skip it. |
| Game's own assets | Reference only | No | Point to them by name or path. Don't copy them into your download. |
Mojang's EULA and Usage Guidelines allow mods, data packs and resource packs. Don't distribute Minecraft's code or assets, and don't present your mod as official. Monetization is limited, so read the guidelines before you charge for anything.
Re-Logic supports tModLoader, which is distributed free on Steam. Mods are shared through its Workshop. Use your own sprites and sounds, and keep mod content inside tModLoader rather than patching the vanilla game.
ConcernedApe welcomes mods, and SMAPI and Content Patcher are the standard tools. You may unpack the game's content files to study them, but ship only your own art and data.
Wube built modding into the game and hosts the official mod portal, which installs mods from inside the game. Reference base-game graphics by path; don't copy them into your zip.
The whole game is a modding platform, and addons go on the Steam Workshop. The big risk is content ripped from other games: models, maps and sounds from other titles get removed and can earn copyright strikes.
Look for an official SDK, editor or Workshop page first. No official support doesn't automatically mean modding is banned, but it does mean reading the EULA carefully and never touching online or anti-cheat systems.
Single-player mods are almost always fine. Online play is where people get banned, so follow three rules:
Use the official channel when there is one. Players trust it and it handles updates for you.
datapack/data/hello/function/starter_kit.mcfunction and change cooked_beef 16 to golden_apple 3.diamond_sword.png and press Edit pixels. Recolor the blade and save./function hello:starter_kit.That's a real, legal mod: your commands, your texture, no game files copied.
| EULA | End User License Agreement: the contract you accepted when you installed the game. It says what you may do with it. |
| Data pack | A Minecraft folder or zip of JSON and function files that changes recipes, loot, advancements and commands without code injection. |
| Resource pack | A Minecraft folder or zip of textures, sounds and models that replaces how things look and sound. |
| Mod loader | A tool that loads compiled mods into a game: Fabric, NeoForge, tModLoader, SMAPI. |
| Content pack | A mod made of data and images that another framework mod reads, such as Content Patcher packs for Stardew Valley. |
| Prototype | In Factorio, a definition of a thing in the game (item, entity, recipe) created in data.lua. |
| Hook | A named moment in the game you can attach code to, like "when a player spawns" or "every frame". |
| Namespace | Your mod's unique ID prefix, such as hello:, so your names never collide with the game's or other mods'. |
| Texture | An image applied to a block, item or model. Minecraft items are usually 16×16 pixels. |