Skill Engine - A Modular Skill Tree Framework for Forge Mods

Skill Engine is not a standalone progression mod.
It does not add gameplay, attributes, or abilities by itself.

Instead, Skill Engine is a framework designed to let other mods create their own highly customizable skill trees, complete with:

Node unlocking
Attribute requirements
Custom icons
Skill point handling
Server synchronization
Requirements & tooltips
Interaction with other progression systems (like Ascend)

If you're looking for a mod that adds skills, this is not it.
If you are a developer who wants to add skill trees to your mod without reinventing everything, Skill Engine is exactly what you need.

Features

JSON-driven Skill Tree System

Mods can register their own skill nodes simply by adding JSON files under:

data/<yourmodid>/skillnodes/*.json

Automatic Node Rendering

Nodes are positioned, displayed, zoomed, panned, and drawn automatically in the Skill Tree GUI.

Icons Support

Use your own textures or vanilla item textures as node icons.

Requirements System

Nodes can specify:

Linked nodes
Prerequisite attributes
Skill costs
Custom tags

The UI automatically displays requirements in tooltips and overlays.

Unlock Logic & Sync

Unlocking is fully handled server-side and synced to the client.

Full API Support

Skill Engine includes a public API class that allows other mods to:

Give skill points
Unlock skill nodes
Check unlock state
Access player skill data
Register or reference nodes

How to Use Skill Engine in Your Mod

Skill Engine is designed to be extremely easy to integrate.

1. Add Skill Engine as a Dependency

In your mods.toml:

[[dependencies.yourmodid]]
    modId="skillengine"
    type="required"
    versionRange="[1.0.0,)"

In your Gradle build:

implementation fg.deobf("net.fretux.skillengine:SkillEngine:<version>")

2. Create Your Skill Nodes (JSON)

Example:

{
  "title": "Basic Strength",
  "description": "You feel your muscles tighten.",
  "cost": 1,
  "position": { "x": -150.0, "y": -50.0 },
  "links": ["skillengine:welcome"],
  "tags": ["yourmodid:strength_1"],
  "icons": "minecraft:textures/item/iron_sword.png",
  "prerequisites": {
    "strength": 10,
    "agility": 5
  }
}

Place this in:

data/yourmodid/skillnodes/basic_strength.json

Skill Engine will automatically detect it and add it to the tree.

3. Use the API in Your Code

Skill Engine exposes a simple API:

SkillEngineAPI.unlockNode(player, SkillEngineAPI.rl("yourmodid", "basic_strength"));
SkillEngineAPI.addSkillPoints(player, 3);
boolean unlocked = SkillEngineAPI.isUnlocked(player, SkillEngineAPI.id("welcome"));

You can interact with the system without touching internal classes.

Users: What Does This Mod Do for Me?

Skill Engine does nothing by itself.
It does not add a skill tree or abilities on its own.

You only need this mod if:

A mod you play depends on Skill Engine
You want to install addons that create skill trees

Fretux's Skill Engine

Ascend