4 Open Source Alternatives to Unity3D
A list of 4 carefully selected open-source alternatives to Unity3D.

The open-source alternatives are ranked based on our custom ranking system and score. This system takes into account various factors to determine the best alternatives.
If you’re looking for alternative features or workflows, here is a prepared detailed list of Unity3D open-source alternatives — each with its own distinctive strengths and key features.
Godot Engine is a free and open‑source game engine crafted for developing both 2D and 3D games across multiple platforms. It leverages an intuitive, scene-driven architecture and robust scripting options to empower creators at every level.

Key Features
- Free and open‑source under the MIT license
- Intuitive node and scene system for flexible game design
- Dedicated 2D engine and robust 3D capabilities
- Supports multiple scripting languages including GDScript, C#, and C++
- Seamless cross-platform deployment for desktop, mobile, web, and consoles
Godot provides a comprehensive toolkit for building everything from simple 2D games to sophisticated 3D projects and XR applications. Its node-based design, support for GDScript, C#, and community-driven language bindings, along with seamless cross-platform deployment, streamlines game development. The engine’s modularity encourages rapid prototyping and customization, while its extensive documentation and community involvement enhance the overall development experience.
Flax Engine is a multi-platform 3D game engine designed to empower developers with an agile and fully featured development environment. It offers full source code access and robust tools to boost productivity and scalability across teams of any size.

Key Features
- Seamless C++ and C# scripting with visual scripting integration
- Automatic batching, instancing, and async asset streaming
- Realtime Global Illumination, GPU Lightmaps Baking, and advanced rendering
- Cross-platform support for Windows, Linux, Android, macOS, iOS, PS4, PS5, Switch, and Xbox
- Lightweight development with full source code access
- Tools for version control, networking, and large world support
Flax Engine delivers high development performance with seamless support for C++, C#, and visual scripting. It optimizes workflows through features like automatic draw calls batching, async asset streaming, and fast compilation. The engine supports multi-platform deployment, extensive lighting and rendering techniques, and a host of tools tailored for both solo indie developers and large teams.
GDevelop is a powerful open-source game engine designed for creators of all levels. It offers an intuitive, no-code event system and drag-and-drop interface to easily build 2D, 3D, and multiplayer games, while supporting cross-platform publishing and a rich asset ecosystem.

Key Features
- Open-source under the MIT license
- Intuitive no-code event system with over 130 behaviors
- Drag-and-drop interface for rapid prototyping
- Cross-platform publishing (iOS, Android, desktop, web)
- Integrated asset store and cloud project management
- Flexible pricing plans including free and tiered subscriptions
GDevelop simplifies game development with its ready-made behaviors and visual event system, allowing users to craft complex game logic without traditional coding. The engine supports seamless export to mobile, desktop, web, and various gaming platforms, and integrates cloud projects, an in-app asset store, and online collaboration tools. Multiple subscription tiers, from a 100% free plan to Silver, Gold, and Pro memberships, cater to beginners, professionals, and educators.
Rebelfork is a lightweight, modular game engine/framework built in C++17 with an integrated WYSIWYG editor and experimental C# bindings. Designed for developers who value a code-first approach, it offers full control over game architecture while being free and open source under the MIT license.
Key Features
- Lightweight and modular design
- Built with C++17 for high performance
- Integrated WYSIWYG editor for streamlined workflow
- Experimental C# bindings for additional flexibility
- Cross-platform support including Desktop, Mobile, Web, and XBox
- Free and open source under the MIT license
Rebelfork delivers a robust environment for developing 3D games and applications, supporting both C++ and C# development. The framework emphasizes direct code execution without the constraints of IDE-driven scripting, ensuring flexibility and performance. It comes with comprehensive documentation, quick start guides, and sample projects to assist developers in leveraging its modular, cross-platform architecture across Windows, Linux, MacOS, Android, iOS, Web, and XBox platforms.
Price comparison of Unity3D open-source alternatives
Tool | Tier 1 | Tier 2 | Tier 3 | Details |
---|---|---|---|---|
![]() | - Royalty-based Pricing | - | - | Learn more |
![]() | $0 Free | $5.49 Silver | $10.99 Gold | Learn more |
* Pricing shown is based on publicly available information and may not reflect current rates. Visit each tool's website for detailed pricing information and additional tiers.
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