Is it only the editor you're replacing when you leave Unity? Rarely. A free, open-source engine covers most indie 2D and 3D projects, a no-code engine suits people who'd rather not script, and a high-end 3D engine suits studios chasing big visuals, but the publishing, ads and in-app purchase tools around your old editor need a plan of their own.
Most people weighing a switch already have something half built, which is why this decision feels heavier than choosing software for a fresh project. You've got scenes, scripts and habits to carry across. Below are ten engines grouped by the job each one does well, then listed A to Z, with a short line on each taken from what its makers say about it.
Questions to settle before you switch engines
What leaves with the editor?
More than people expect. The company's own homepage is organised as Develop, Deploy and Grow, and the engine sits next to LiveOps, user acquisition, in-app purchase, monetization and advertising products. If your game earns through ads or in-app purchases, or you run live events through those tools, leaving means walking away from that wider stack as well as the editor.
Write down every one of those services you rely on before you commit. The engines below all describe themselves around building games, not around running your ads or finding your players, so each service on that list needs its own answer.
Are you making 2D, 3D or both?
This narrows the field fast. A couple of engines here are built around 2D and pitched at beginners, several describe themselves as covering 2D and 3D, and a few put 3D first with modular or full-source setups aimed at bigger teams. A small pixel-art game and a 3D world with physics need very different things, so be honest about which one you're making right now, not the one you'd like to make one day.
Do you want to write code at all?
If the answer's no, look at the no-code engine and the engines that offer visual scripting first. If you're happy in code, the language question below matters more than which editor looks nicest in a screenshot.
Which language does your team already know?
The engines here name C#, C++, Rust and visual scripting among their options. Switching engine and language in the same month is two big changes at once, and that's where projects stall. If your team writes C# today, an engine that uses it lets you keep that skill while you learn a new editor. If someone on the team loves Rust, there's an engine built in it.
Who will look after the engine your game depends on?
Several of these engines are open source and publish their source code, which means your team can read it and change it if you need to. Others come from a single company and follow that company's plans. Neither route is wrong, but you should know which one you're choosing before you rebuild a game on top of it.
Ten engines, sorted by what they do well
For big 3D projects, Unreal Engine is the one Epic pitches as AAA-grade, running on Windows, macOS and Linux with Blueprint visual scripting. O3DE takes a modular route, adding features through Gems, and names education and robotics next to games. Flax Engine hands you the full source code, with C++, C# and visual scripting.
For 2D and first games, GameMaker pitches itself at beginners and indie developers, and GDevelop lets you build without code and publish to Steam and app stores.
For small, cross-platform builds, Defold describes an all-in-one engine with a small footprint, while Cocos Creator handles 2D and 3D real-time content and is also used outside games.
For open-source all-rounders, Godot covers 2D, 3D, cross-platform projects and XR. Stride is the C# choice, with VR content on desktop, and Bevy is built in Rust around an Entity Component System.
| Tool | Kind of engine | Who it suits |
|---|---|---|
| Bevy | Rust ECS engine | Rust coders who like data-driven design |
| Cocos Creator | Cross-platform 2D/3D engine | Real-time content in games and beyond |
| Defold | Lightweight cross-platform engine | Small, cross-platform 2D and 3D games |
| Flax Engine | C#/C++ engine | Teams wanting the full engine source |
| GameMaker | 2D engine for beginners | First 2D games |
| GDevelop | No-code engine | Building games without writing code |
| Godot | Open-source 2D/3D engine | Indie 2D, 3D and XR projects |
| O3DE | Modular open 3D engine | Gaming, education and robotics projects |
| Stride | C# open-source engine | C# developers making desktop games or VR |
| Unreal Engine | High-end 3D engine | Studios chasing high-end 3D |
The full set follows in no particular order beyond the alphabet. Each line comes from what the maker says about its own engine.
Bevy
Best for: Rust programmers who want a data-driven engine built on an Entity Component System; the project says it's free and open source forever.
Cocos Creator
Best for: Cross-platform 2D and 3D real-time content, in games and outside them; the vendor calls it an efficient and lightweight graphics engine.
Defold
Best for: Small-footprint 2D and 3D games for several platforms, from an all-in-one engine with available source that its makers say is free forever.
Flax Engine
Best for: Developers who want full source code and a choice of C++, C# or visual scripting; the vendor sums it up as full source, full power.
GameMaker
Best for: Beginners and indie developers making 2D games; the vendor's pitch is that you can make games with no experience required.
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GDevelop
Best for: Making games without code and publishing them to Steam and app stores, from what the project calls an open-source, no-code engine.
Godot
Best for: Free, open-source work across 2D, 3D, cross-platform projects and XR; the project's own line is your free, open-source game engine.
O3DE
Best for: Teams in gaming, education or robotics who'd like to add features through modular Gems on an open 3D engine.
Stride
Best for: C# developers making 2D and 3D games or VR content for desktop; the project points to next-gen graphics API support.
Unreal Engine
Best for: Studios after high-end 3D on Windows, macOS or Linux, with the Unreal Editor and Blueprint visual scripting that Epic puts front and centre.
Where a small indie team should begin
Start with the smallest real piece of your game, not a tutorial. Take one level, one character and one menu from your current project and rebuild them in two engines from the group that matches your job. You'll learn more from a weekend of that than from a month of reading feature pages, because the friction shows up in your own work, not in someone else's demo.
How do you trial two engines in one weekend?
- Copy one small scene, its art and its main script out of your current project.
- Install two engines from the same group and open each one's own starter template.
- Rebuild the scene in both, noting every point where you got stuck or had to search for help.
- Export a test build to the platform you ship on most and run it there, not only in the editor.
- List the services from your old stack that the build still needs, such as ads or in-app purchases.
What if your game relies on ads and in-app purchases?
Then sort those out before launch day, not after. Make a list of each service your game uses today, then check what the new engine's own site says about the platforms and stores you publish to. If licence terms are the worry, my piece on whether that open-source engine is free to use walks through it, and this round-up of free game engines goes wider. Still weighing the two big commercial engines against each other? Here's my side-by-side of them.
Do you make a game engine? Tool makers can ask to be considered for a featured place on this list.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
Can I move an existing project to a different engine?
Not with one click. Expect to rebuild scenes and rewrite scripts, especially if the new engine uses a different language. Move one small slice first so you can see how much of your work carries over.
Is there a free engine that handles both 2D and 3D?
Several engines in this list describe themselves as free and open source and cover both 2D and 3D. Read each project's own site for its licence terms before you build anything you plan to sell.
Which engines let me make a game without code?
One engine here describes itself as no-code, and a few others offer visual scripting next to code. The table shows what kind of engine each one is.
Do I need to know C# or C++?
Not for every engine. Some use C#, some C++ or Rust, and some offer visual scripting, so match the engine to the language your team already writes.
What happens to my ads and in-app purchases if I switch?
They don't move across on their own. Plan each service separately and check what the new engine's site says about the stores and platforms you publish to.
Can these engines be used for things other than games?
Some say so. One names education and robotics alongside games, and another mentions real-time content outside games.
