OpenCAGE Documentation

Welcome!

OpenCAGE is a free, open-source modding toolkit for Alien: Isolation. CAGE, the Creative Assembly Game Editor the game was made with, was never released to the public — OpenCAGE brings back much of what it could do, through years of reverse engineering.

Explore every level in a 3D Viewport, edit the game's node-based scripts or write your own, import models, materials, textures and animations, and build brand new levels from scratch. With Live Link, your edits appear in the running game as you make them — and when you're done, package it all up as a mod anyone can install.

New here? Grab OpenCAGE from Steam, then start with the Scripting Introduction — every tool has its own guide in the sections below, and the ? in a window's title bar opens its guide. Join the Discord for tips from the community, and to show off what you're working on. If OpenCAGE crashes, Help → Open Logs Folder has the crash log to attach when you report it (Help → Report Bug).

Just want to play mods other people have made? See Installing Mods — no modding knowledge needed.

Download on Steam

Join the Discord

Star on GitHub

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Just want to play with mods? The Mod Manager installs them for you, lets you use lots of them at once, and takes them out again whenever you like. Made something yourself? Turn it into a mod anyone can install.

Installing Mods

Add, install, combine, update and remove mods with the Mod Manager.

Making Mods

Turn your changes into a mod to share, and make it work well with other mods.

Start here if you're new to OpenCAGE — how Cathode scripting and the script editor work, the Viewport and Options, multiple game installs, and taking backups before you experiment.

Scripting Introduction

An intro to Cathode's scripting system and overview of OpenCAGE's script editor.

Viewport

A guide to OpenCAGE's 3D Viewport.

Options

What each Options menu setting does in the script editor.

Multiple Game Installs

Backup Manager

Snapshot and restore level files, plus reset global configs to stock.

Try your changes out in Alien: Isolation — boot straight into a level, edit it while it runs with Live Link, put debug text on screen to see what your scripts are doing, and open the in-game Debug Menu to look inside the running level.

Launch Game

Starting levels, debug tools, game options and UI tweaks from OpenCAGE's Launch Game window.

Live Link

Edit the running game without a reload: build and tweak scripts, place and tune lights and props in the game's own render, call entity methods, stop scripts at breakpoints, capture cubemaps, and link the game and Viewport cameras.

Debug Text & Markers

Put text, script values and position markers on screen in the game to see what a script is doing, or stop it at a breakpoint.

Debug Menu

An in-game debug menu: see what each character senses, sees and is doing, its behaviour and animation trees and skeleton, what the game's sound is doing, and flick the game's own rendering switches.

Rebuild a level after changing its geometry, port composites between levels, make new levels from scratch, or have an AI assistant build them for you.

Save and Build

Regenerate a level's lighting, navmesh, collision, cover and sound after changing its geometry.

Composite Porting

Import and export composites, with every asset they depend on, between levels — or as .ocp packages to share.

Create Level

Make a brand-new level from scratch, seeded with composites from any other level.

AI Assistants

Let an AI assistant such as Claude build and edit levels in OpenCAGE, through the Model Context Protocol.

Dedicated editors for function entities that need more than the node graph — timelines, trigger sequences, bindings, and character accessory sets.

CAGEAnimation Editor

Edit CAGEAnimation timelines — float curves, string events, and animation entity bindings.

Character Editor

Edit Character accessory sets — body composites, skeletons, asset types, and NPC metadata.

TriggerSequence Editor

Edit TriggerSequence targets, delays, and start/finished method pins.

Tools for editing engine configurations, skybox stars, material remaps, character AI trees, and the game's on-screen text.

Configurations

A guide to modifying the various configurations within the engine.

Galaxy Editor

Define and regenerate skybox starfields for a level.

Material Mapping Editor

Create From→To material remaps for models and instances.

Behaviour Tree Editor

Edit global character AI trees in the external Behaviour Tree Editor.

Localisation Editor

Edit and add the game's on-screen text across all nine shipped languages.

Editors for level and game resources — meshes, collision and physics, UI.PAK, materials, textures, animation clips and trees, blend sets, and sound.

Model Editor

Browse, import, export, and edit level meshes.

Collision Editor

Browse, preview, and import the collision proxies objects are solid with.

Physics System Editor

Edit rigid body mass and friction, and import new physics props.

UI Editor

Extract, replace, add and remove files in the game's UI.PAK archive.

Material Editor

Edit level visual materials — samplers, features, and shader parameters.

Texture Editor

Browse, import, export, and replace level textures — DDS, PNG, JPEG, TGA and more.

Animation Editor

Browse, preview, export and import animation clips — with retargeting for outside rigs.

Animation Tree Editor

Browse and edit animation trees — clip selection, blends, parameters, and graph wiring.

Blend Set Editor

Edit the parametric blends that mix several clips into one continuous motion.

Sound Events

Preview, export and replace the audio behind the game's Wwise sound events.

Deep-dive catalogues for scripting APIs, AI behaviour tree nodes, and animation tree nodes.

Cathode Entities

A complete look at all entities and interfaces within the Cathode scripting system.

Cathode Enums

A complete look at all enums available within the Cathode engine.

Behaviour Tree Nodes

A complete look at the nodes available within behaviour trees in the game.

Animation Tree Nodes

A complete look at animation tree node types, parameters, and graph pins.

Quick reference for map folder names and campaign mission IDs.

Level Names

Map names used in OpenCAGE and what each level contains.

Mission IDs

Campaign mission IDs, codenames, and cut missions.