Fio — Liminal World Editor & Procedural Engine

Unified editor and runtime inspired by Radiant and Hammer. Optimised for low-power CPUs

Key Features

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

💾 Download Binaries for Windows/macOS/Linux | Wiki | Changelog

or use the included Dockerfile or run from source

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Why Fio exists

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 non-Euclidean level design without engine modifications

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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

• OpenGL 3.3 forward renderer
• Dynamic lighting, shadows, fog, glass and water
• Frustum culling
• World portals — non-Euclidean view-through portals with stencil-buffer masking, oblique near-plane clipping, and I/O-driven fade transitions. Place two portals, link them by name, walk through seamlessly.

Under the Hood

• Python 3.10+ runtime
• NumPy used for batch numeric operations and scene updates
• Multi-threaded subsystems (render / simulation separation where applicable)
• Designed for CPU-bound performance on low-power hardware (ARM-class)
• Runtime state is shared between editor and engine layers; no serialization boundary during play mode

🗎 Modular architecture, fully open source (MIT License)

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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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