Fio

Fio is a real-time liminal level editor with an integrated game engine, built to recapture the immediacy of classic tools like Radiant and Hammer. It enables developers to build levels and instantly play them without compilation or lightmap baking. Key features include:

• Real-time workflow: Build levels and walk around instantly with no compile steps
• Built-in game engine: Unified forward renderer with real-time lighting and stencil shadows
• Classic brush-based editing: Familiar Quake/Hammer-style workflow with CSG operations
• Entity I/O system: Inspired by Half-Life 2 with logic, triggers, lights, and speakers
• Optimized for mobile: Targets Snapdragon 8CX and OpenGL 3.3 for mobile CPU performance
• Advanced rendering: Fog, glass, and water shaders with configurable surface parameters
• Asset support: OBJ model import and terrain generation capabilities
• Versioned JSON format: Level files with integrity checks and version control

Fio is ideal for game developers creating retro-style FPS games, architectural visualization, or experimental projects requiring rapid iteration. The MIT-licensed open source codebase makes it suitable for research, education, and commercial projects.