Fio — Liminal World Editor & Procedural Engine

Unified editor and runtime inspired by Radiant and Hammer.

Fio is a modern, instant-iteration take on classic CSG level editors
Designed on low-power ARM hardware with an efficiency-first philosophy.

Key Features

• Hit "Play" instantly: no import, compile or bake step
• Edit and play in the same runtime
• Classic brush-based editing with arbitrary convex polyhedra
• Non-Euclidean portal connections between any two points in a level
• Generate fully playable procedural maps with two clicks
• Entity I/O logic system inspired by Source engine
• Local split-screen multiplayer
• Export projects as portable, self-contained packages
• Designed to bring back the immediacy of classic Radiant/Worldcraft workflows

💾 Download Binaries for Windows/macOS/Linux

Documentation: Wiki | Changelog

or use the included Dockerfile or run from source

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Why Fio exists

An engine built for rapid experimentation. Fio explores a unified approach to level editing and runtime simulation:

• Reducing friction between authoring and execution

• Reintroducing brush/CSG-based workflows in a modern runtime

• Treating gameplay logic as a visible, editable system

• Supporting rapid experimental iteration in rendering and world design

• Enabling native non-Euclidean level design via world portals

• Persistent global key/value storage allows maps to influence later maps and enables branching narratives.

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Logic & Gameplay

• 16 included example maps
• Monsters with node-based pathfinding
• Triggers, timers, and logic gates
• Procedural terrain and liminal level generators
• Keys/values can be stored globally (persists across level changes)

Rendering

• Lean OpenGL 3.3 renderer engineered for performance and broad compatibility.
• Dynamic lighting, shadows, fog, glass and water
• Frustum culling
• Native world portals — seamless non-Euclidean connections between arbitrary locations using stencil-buffer masking and oblique near-plane clipping. No BSP, VIS/PVS preprocessing or offline visibility compilation is required.

Under the Hood

• Python 3.10+ Core: High-level logic and orchestration paired with C-accelerated NumPy arrays for vector math, scene transformations, and batch numeric processing.
• Hardware-Conscious Design: Optimized for low-power, ARM-class CPUs—minimizing unnecessary memory allocations and redundant compute cycles before leaning on raw GPU power.
• Zero Serialization Overhead: Editor and engine share the same runtime memory state, enabling instant execution with no compile, bake, or scene-deserialization delay.
• Modular Multi-Threading: Subsystems (render pipeline, physics, and world simulation) are strictly decoupled to keep framerates steady during heavy runtime tasks.
• Open Architecture: Fully open-source, modular codebase (MIT License) designed for easy extendability and low-level experimentation.

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🚀 Quickstart:

Python 3.10+ is required

git clone https://github.com/ViciousSquid/Fio.git
cd Fio
python -m venv venv
source venv/bin/activate  # or venv\Scripts\activate (Windows)
pip install -r requirements.txt
python main.py

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🤝 Contributing

Contributions, feedback, and experiments are welcome. Check issues or open a discussion.

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