The best alternative to Unity is Godot Engine, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Unity and many of them are so hopefully you can find a suitable replacement. Other interesting alternatives to Unity are Unreal Engine, Redot Engine, CRYENGINE and Bevy Game Engine.
Godot Engine is a feature-packed, cross-platform game engine to create 2D and 3D games from a unified interface. It provides a comprehensive set of common tools, so that users can focus on making games without having to reinvent the wheel.
Argentina
Unreal Engine is a professional suite of tools and technologies used for building high-quality games across a range of platforms. Unreal Engine’s rendering architecture enables developers to achieve stunning visuals and also scale elegantly to lower-end systems.
United States
Redot Engine is a feature-packed, cross-platform fork of the Godot game engine to create 2D and 3D games from a unified interface. It provides a comprehensive set of common tools, so that users can focus on making games without having to reinvent the wheel.
The most powerful game development platform is now available to everyone. Full engine source code. All features. No royalties. No obligations. No license fee.
Germany
EU
A refreshingly simple data-driven game engine built in Rust. Free and Open Source Forever!
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D engine that enables developers and content creators to build AAA games, cinema-quality 3D worlds, and high-fidelity simulations without any fees or commercial obligations.
United States
PlayCanvas is the world’s easiest to use WebGL Game Engine. It’s free, it’s open source and it’s backed by amazing developer tools.
United Kingdom
Fibbo is a free and open-source web-based game engine that allows you to create interactive experiences using JavaScript, right in your browser.
Xogot brings the full power of the Godot game engine to iPad. With a native iPad experience designed for touch, you can create, test, and share games wherever inspiration strikes.
One framework for creating powerful cross-platform games. The spiritual successor to XNA with 1000's of titles shipped across desktop, mobile, and console platforms. MonoGame is a fully managed .NET open source game framework without any black boxes.
Create anything you can imagine with Roblox's free and immersive creation engine. Roblox Studio lets you create anything and release with one click to smartphones, tablets, desktops, consoles, and virtual reality devices.
United States
Range Engine is a light and powerful game engine and 3D software, made based on Blender Game Engine with improvements from UPBGE.
