Fio
A downloadable tool for Windows, macOS, and Linux
A modular 3D engine and brush-based CSG level editor inspired by Radiant and Hammer
Key Features
- 🔁 Runtime-switchable Forward & Deferred rendering
- 🎨 Unified shader system across pipelines
- 🧠 Entity I/O logic system inspired by Source engine
- 🧱 Classic brush-based CSG editing
- Designed to bring back the immediacy of classic Radiant/Worldcraft workflows
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Core Workflow
- Editor and engine run as a unified environment
- Hit play instantly — no compile or bake step
- Iterate on gameplay and logic in real-time
- Design, test, and refine in a single environment
- Creations can be published and shared
Logic & Gameplay
- Entity I/O system (Half-Life 2–style)
- Visual scripting (25 examples)
- NPCs/monsters
- Node pathfinding
- Logic Gates, Triggers, Timers
Rendering
- Dual rendering pipelines (Forward & Deferred, switchable at runtime)
- Real-time dynamic lighting with shadows
- Fog, glass, water and overbright shaders
- Moving and rotating brushes
- World Portals (Prey 2006 style)
- Frustum culling
Technical
- JSON level format
- OBJ model support
- OpenGL 3.3 target
- Optimized for Snapdragon 8CX / Windows-on-ARM
🗎 Modular architecture, fully open source (MIT License)
Official repo: ViciousSquid/Fio
Download
Install instructions
This app is unsigned (no Apple/Microsoft certificate).
macOS/Windows will warn you before opening:
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macOS Instructions:
1. Download and unzip
2. Right-click Fio.app
3. Click "Open"
4. macOS blocks the launch,
5. Go into Privacy & Security and click the "Allow" button on the section that shows that the app was blocked.
Comments
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I just released version 1.2.6.0 with PORTALS - have some fun with them :-)
Also the ability export creations as package files which can be shared - and a new fullscreen mode (F12 during play mode)
plus example maps to demonstrate the new stuff - changelog
This is awesome can’t wait to see more also super excited for the split screen controller gaming stuff next this is really damn cool!!! Can’t wait to try the new features out
I found a BUG preventing a Spawner entity from spawning a Monster - fixed and released new version 1.2.6.1
Please read the changelog
This looks super cool going to give it a try, how good is it for building full games by chance? I had some other questions but am gonna give it a shot and play around with it. Is there a chance theres local coop/splitscreen implemented in with the scripting tools provided (this is just my favorite thing and want to add it in all my stuff)? Is it pretty extensive to use for different kinds of games and building your own systems in engine? This just looks really cool so I was just curious about some stuff!
Hi thanks for your message. Everything made cannot yet be exported but I'm working on that - in future this will be capable of exporting self-contained games.
I like your idea of split-screen and I will work to implement this
I would absolutely love the split screen idea for me it’s really important and not a lot of game engines allow for it easily this is really cool by the way I was having so much fun just messing around and building little levels last night. One suggestion with the monsters and entities it would be really cool to add your own icons in the future. Thought the monster icon was cute and thought it would be neat to change the little icons to whatever you would like. Loving it so far going to keep this saved and watch for any updates!!!!
Version 1.2.6.0 was just released with the ability to customise monster sprites in the 2D view.
Split-screen coming next! changelog