Alternatives / Unity
Looking for an open source Unity alternative? We compared 4 open source game engines and frameworks by license, languages, editors, and platforms. They range from a full engine to a no-code engine, a code-first framework, and a platform built on Source 2, and one of them is only partly open.
Written by Maxime DERAME
Last updated:
| Alternative | Best for | License |
|---|---|---|
| Godot | Closest full engine for 2D, 3D, and XR | MIT |
| GDevelop | No-code games with a visual event system | MIT |
| MonoGame | Code-first C# games on many platforms | Microsoft Public License (MS-PL) |
| s&box | Games on Source 2 and .NET (partly open, platform-bound) | MIT + EULA (native binaries) |
We looked for open-source tools that overlap with Unity's core: building 2D and 3D games with an editor or framework and exporting to several platforms. We verified each project's license, recent activity, stars, and platforms in its repository. Unity is a proprietary engine with runtime fees in its past, so we flag license terms and platform lock-in. See our methodology for the full criteria.
s&box's engine source code is MIT-licensed, but some native binaries are under the s&box EULA, so it is only partly open source. Games are played through the s&box platform rather than shipped as standalone executables, which ties your audience to it, and it suits prototyping and small to medium projects.
Godot is the closest: a full-featured 2D, 3D, and XR engine with its own scripting language, a scene editor, and export to many platforms, under MIT with no fees or royalties. It has a steeper learning curve than GDevelop, and its node-and-scene model differs from Unity's.
GDevelop is a free engine with a visual event system and one-click publishing to Steam, mobile, web, and desktop, so it offers less direct code control. MonoGame is a C# and .NET framework for desktop, mobile, and console games with no editor or scene graph, and console access requires approved developer status.
Godot and GDevelop are MIT, MonoGame is under the Microsoft Public License except for a few portions, and s&box's engine source is MIT with EULA-covered native binaries.
Godot, GDevelop, MonoGame, and s&box all had commits within days of this update.
Unity is a proprietary engine whose pricing and terms have changed in ways that worried developers, with closed source and dependence on its company for the future of your game. Open-source engines have no licensing fees or royalties, let you inspect and modify the engine, and keep your games independent of one vendor, at the cost of smaller asset stores and fewer ready-made integrations.
Godot is an MIT-licensed, full-featured 2D, 3D, and XR game engine with its own scripting language, a scene editor, and export to multiple platforms, with no licensing fees or royalties. It has a steeper learning curve than GDevelop, and its node-and-scene model differs from many other engines.
Pricing: Free and open source; no royalties.
GDevelop is a free, open-source 2D, 3D, and multiplayer game engine for everyone, with a visual event system, AI-assisted help, built-in tutorials, and one-click publishing to Steam, mobile, web, and desktop. The core library, engines, IDE, and extensions are MIT-licensed, and online services and an asset store are separate.
Pricing: Free; online services and commercial support are paid.
MonoGame is an open-source C# and .NET framework for building games that run on desktop, mobile, and major consoles from one codebase, owned by a nonprofit that relies on donations. It is under the Microsoft Public License except for a few portions, has no editor or scene graph, and console access requires approved developer status.
Pricing: Free and open source; no royalties or runtime fees.
s&box is a game engine and platform built on Valve's Source 2 and .NET, with a modern editor, C# scripting, live reloading, and built-in multiplayer. The engine source is MIT-licensed, but certain native binaries are under the s&box EULA, and games are played through the s&box platform rather than shipped as standalone executables.
Pricing: Free to use; check the EULA for terms.
| Alternative | Type | License | Editor | Best for |
|---|---|---|---|---|
| Godot | Game engine | MIT | Yes | 2D, 3D, and XR games |
| GDevelop | No-code game engine | MIT | Yes (visual events) | Games without code |
| MonoGame | C# framework | Microsoft Public License | No | Custom engines and XNA ports |
| s&box | Source 2 platform | MIT + EULA binaries | Yes | Prototyping on Source 2 |
Want a full open-source engine
Godot is an MIT 2D, 3D, and XR engine with a scene editor and export to many platforms, with no fees or royalties.
Want to make games without code
GDevelop uses a visual event system and publishes to Steam, mobile, web, and desktop, under MIT.
Prefer coding in C#
MonoGame is a C# and .NET framework for desktop, mobile, and console games with no runtime fees.
Want to build on Source 2 and .NET
s&box offers C# scripting, live reloading, and built-in multiplayer, but games run through its platform and some binaries are under an EULA.