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Top 23 C++ Game Engine Projects
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I noticed that Godot Engine Apple Vision OS support is merged today. <3
https://github.com/godotengine/godot/pull/105628
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InfluxDB
InfluxDB – Built for High-Performance Time Series Workloads. InfluxDB 3 OSS is now GA. Transform, enrich, and act on time series data directly in the database. Automate critical tasks and eliminate the need to move data externally. Download now.
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Cocos2d
Cocos2d-x is a suite of open-source, cross-platform, game-development tools utilized by millions of developers across the globe. Its core has evolved to serve as the foundation for Cocos Creator 1.x & 2.x.
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Minetest
Luanti (formerly Minetest) is an open source voxel game-creation platform with easy modding and game creation
Project mention: The psychology behind why children are hooked on Minecraft | news.ycombinator.com | 2025-04-04Yes, and it isn't for every player. Funny story time: I bring online sometime a Luanti [1] server to playtest the game I made in a multiplayer context. One time someone joined and after a few minutes visiting, they asked "So, what is the goal?". I wasn't expecting that. MC may be popular, but one doesn't join a Luanti game server by accident, and most of them are MC- or at least MMORPG-like.
Still, although there's no set goals like in other games, this style of game has to have "affordances" for goals. Even the building activity in MC is not "free", as monsters are there to get in the way of the players' projects.
I also think that the social aspect is crucial, in the sense that having fun building things doesn't last, because one eventually runs out of ideas. Showing to others what you have achieved is an important part of it. Does art exist without an audience ? [2]
I think it is interesting to note that the fact that MC's world is fully editable by players is what drove the choice for the voxel technology, which was the only one allowing it with a normal PC at the time.
[1] https://www.luanti.org/
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cocos-engine
Cocos simplifies game creation and distribution with Cocos Creator, a free, open-source, cross-platform game engine. Empowering millions of developers to create high-performance, engaging 2D/3D games and instant web entertainment.
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o3de
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.
O3DE came from Amazon Lumberyard which came from CryEngine, so it's quite possibly one of the better looking open source 3D game engines that you can currently get, no strings attached: https://github.com/o3de/o3de
Sadly, you need to put in a lot of work to get good results out of it (neither of its predecessors had a reputation for being easy to work with) and for whatever reason many studios aren't exactly rushing to invest a bunch of time into it (many just go for Unreal Engine 5, or stick with Unity etc., indies often opt for Godot), so you don't get much past simple example projects. Part of this is probably that it never generated a lot of hype or much of a community around it.
Godot has a big community around it and is maturing pretty quickly, the early versions were pretty rough when it came to 3D (2.X and 3.X), but it's better now. Not as stable as Unity or Unreal but those have had the advantage of lots of years of work put into them, by more people than Godot has up until now.
There's also more niche options like Stride (https://www.stride3d.net/) and Flax (https://flaxengine.com/) but they suffer from the same issues as O3DE, even if otherwise are promising.
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JoltPhysics
A multi core friendly rigid body physics and collision detection library. Written in C++. Suitable for games and VR applications. Used by Horizon Forbidden West.
Project mention: Jolt: Physics and collision detection library, used by Horizon Forbidden West | news.ycombinator.com | 2024-09-03 -
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defold
Defold is a completely free to use game engine for development of desktop, mobile and web games.
Project mention: Free high-performance cross-platform game engine | news.ycombinator.com | 2025-04-18 -
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Panda3D
Powerful, mature open-source cross-platform game engine for Python and C++, developed by Disney and CMU
A GitHub repository (like this one)
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NoahGameFrame
A fast, scalable, distributed game server engine/framework for C++, include the actor library, network library, can be used as a real time multiplayer game engine ( MMO RPG/MOBA ), which support C#/Lua script/ Unity3d, Cocos2dx and plan to support Unreal.
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Spring RTS game engine
A powerful free cross-platform RTS game engine. - Report issues at https://springrts.com/mantis/ (by spring)
In the Spring/Recoil RTS game engine[1] we adapted Lua to have deterministic execution allowing synchronous multiplayer simulation. In addition we relatively easily implemented a precise[2] serialization of the Lua VM, allowing us to support save/load for games with no code required from their side.
In other languages these would require much more effort.
[1] https://github.com/spring/spring or https://github.com/beyond-all-reason/spring (yay for forks!)
[2] Preserving the order of iteration on items in a hash table.
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xray-16
Improved version of the X-Ray Engine, the game engine used in the world-famous S.T.A.L.K.E.R. game series by GSC Game World. Join OpenXRay! ;)
View the Project on GitHub
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Project mention: fheroes2: A recreation of Heroes of Might and Magic II game engine | news.ycombinator.com | 2025-01-08
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This is great.
If you're into these retro games there's a couple of others that have been fun:
Ultimate Stunts: https://www.ultimatestunts.nl/
Descent 3: https://github.com/DescentDevelopers/Descent3 (if you own the original, or on other platforms if you want to buy)
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Project mention: Antirez/load81: SDL based Lua programming environment for kids similar to Codea | news.ycombinator.com | 2024-10-26
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NOTE:
The open source projects on this list are ordered by number of github stars.
The number of mentions indicates repo mentiontions in the last 12 Months or
since we started tracking (Dec 2020).
C++ Game Engine discussion
C++ Game Engine related posts
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VisionOS Godot Engine support merged
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OpenXRay: Reviving the S.T.A.L.K.E.R. Legacy
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Native visionOS platform support in Godot
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(Godot Engine) Native VisionOS Platform Support
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Show HN: My non-vibe-coded game engine
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The psychology behind why children are hooked on Minecraft
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Redesigning the Reference Component on Gabe the Bear Blog
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A note from our sponsor - SaaSHub
www.saashub.com | 23 Jun 2025
Index
What are some of the best open-source Game Engine projects in C++? This list will help you:
| # | Project | Stars |
|---|---|---|
| 1 | Godot | 98,203 |
| 2 | imgui | 66,233 |
| 3 | Cocos2d | 18,573 |
| 4 | Minetest | 11,551 |
| 5 | entt | 11,199 |
| 6 | cocos-engine | 8,768 |
| 7 | o3de | 8,325 |
| 8 | JoltPhysics | 8,002 |
| 9 | Piccolo | 6,260 |
| 10 | defold | 5,145 |
| 11 | magnum | 4,986 |
| 12 | Panda3D | 4,810 |
| 13 | GamePlay | 4,635 |
| 14 | NoahGameFrame | 4,073 |
| 15 | Spring RTS game engine | 3,670 |
| 16 | lumixengine | 3,625 |
| 17 | Torque3D | 3,350 |
| 18 | xray-16 | 3,247 |
| 19 | fheroes2 | 2,953 |
| 20 | Descent3 | 2,938 |
| 21 | corona | 2,659 |
| 22 | SpartanEngine | 2,475 |
| 23 | Polycode | 2,390 |
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