Game Engines

Godot119.8k★

Godot is a full game engine for 2D and 3D games, and it costs nothing at any size: MIT license, no royalties, no seat fees, no revenue threshold. It's the open source answer to Unity and Unreal, and plenty of indies moved over after Unity's Runtime Fee mess (since cancelled). Setup is a download. The editor runs on Windows, macOS and Linux, plus an experimental Android build. You script in GDScript (Python-flavored, made for Godot) or C#, and drop to C or C++ through GDExtension when you need speed. Exports cover desktop, Android, iOS and the web, and releases are steady: 4.7 shipped in June. There is no paid tier. Solo devs and small studios: free, and the obvious first pick for 2D. Medium studios: free, solid for 2D and stylized 3D. Large teams chasing photoreal 3D: Unreal still has the edge. The catch: consoles. Platform NDAs mean Godot can't ship Switch, PlayStation or Xbox exports itself, so you go through paid middleware like W4 Games or a porting house. And C# projects in Godot 4 still can't export to the web, with C# on Android and iOS labeled experimental. Browser game? Use GDScript. iOS exports need a Mac.

Bevy49.6k★

Bevy is a game engine written in Rust and built around an entity component system (ECS): you build game objects by snapping data components together instead of inheriting from classes. It renders 2D and 3D, targets Windows, macOS, Linux, the web, iOS and Android, and it's free under your choice of MIT or Apache 2.0. No royalties, no seats, no revenue share. There's nothing to host. Add it with Cargo and write code. Hot reloading covers scenes, textures and meshes; gameplay changes still mean a recompile. A nonprofit foundation pays maintainers out of donations, and version 0.20 shipped in early October. Solo Rust developers and small code-first teams: free, and a real option. Medium and large studios that need an editor and a stable API: Godot or Unreal for now. Unreal is free until $1M in lifetime gross revenue per product, then takes 5%. The catch: Bevy is pre-1.0 and says so. A release with breaking API changes lands about every three months, and migrations aren't always easy. There's still no visual editor. Recent releases ship editor building blocks (UI widgets, a scene format, a remote inspector in progress), not the editor itself. Everything is code.

GDevelop28.6k★

GDevelop builds 2D and 3D games without code: you wire up events (conditions and actions) and attach behaviors to objects instead of writing scripts. No C# or GDScript to learn first. The editor and engine are MIT licensed and free, including for games you sell. The paid part is GDevelop's hosted services: cloud projects, one-click cloud builds, leaderboards, multiplayer lobbies and AI credits. Skip all of it by exporting manually as a Cordova or Electron project and building with the native tools yourself. A free account gets 3 cloud projects plus 1 desktop and 1 Android build a day, with no iOS builds. Silver is $7.99/month ($54.99/year) for 10 builds a day. Gold is $13.99/month ($95.99/year) and adds 15 iOS builds a month. Pro is $39.99/month ($399.99/year) and raises iOS builds to 30 a month. Solo hobbyists: free. Small teams shipping to phones: Gold. Studios: Pro. The catch: if your company or client had more than $50K in revenue or funding over the prior 12 months and you use a GDevelop account, Pro is required. Free accounts must also keep the GDevelop logo or a watermark in exported games, and new subscriptions went up 20% in January 2026.

cocos-engine9.9k★

Cocos Creator is a free game engine with a visual editor, scene graph, and cross-platform export to iOS, Android, web, and desktop. Cocos has been around since 2010 (originally Cocos2d-x) and is huge in Asia, particularly China. The engine handles rendering, physics, animation, UI, and audio. The editor is TypeScript-based, which is unusual for game engines but means web developers can jump in without learning C# or C++. It also exports to native platforms via C++. Completely free. The license situation is a bit unusual (custom license, not a standard OSI one), but there are no royalties, no revenue caps, and no paid tiers. Solo indie developers and small studios targeting mobile will find this compelling. The 2D workflow is particularly strong. For 3D, it's improving but still behind Unity and Godot in tooling maturity. The catch: English documentation is spotty. The community is predominantly Chinese-speaking. If you don't read Mandarin, you'll miss a lot of resources and forum help.

mineflayer7.7k★

mineflayer turns a Minecraft account into a programmable client. Point it at a server, write JavaScript, and your bot can dig, build, fight, navigate terrain, and chat. MIT licensed, runs on Node, also callable from Python. There is nothing to host. Install the npm package, hand it a server URL plus credentials, and you have a bot. Pathfinding works out of the box. Where it gets hard is what you ask it to do. Coordinating multiple bots, surviving mob attacks, or building structures larger than a few blocks means writing real game logic. The library tracks underlying protocol versions, so new Minecraft releases usually work within an update or two. This is the standard for Minecraft automation. Hobbyists, modders, AI experimenters running LLM-powered bots, and researchers studying autonomous agents in 3D environments all use mineflayer because the alternatives are protocol libraries that hand you raw packets. Start here unless you have a reason not to. The catch: Minecraft is owned by Microsoft and the protocol changes with major updates. Expect occasional version pinning while maintainers catch up.

fheroes23.7k★

fheroes2 rebuilds the engine behind Heroes of Might and Magic II, the 1996 turn-based strategy classic, from scratch. You bring the original game files and it runs them with high-resolution graphics, better AI, bug fixes and a cleaned-up interface. GPL-2.0, free, funded by donations. Installation is the easy part. There are builds for Windows, macOS, Linux, Android, PlayStation Vita and Nintendo Switch, plus Flatpak, Homebrew and AUR packages. The installer pulls resources from a copy you already own, or downloads the free English demo if you don't. This is for people who want to play the game on modern hardware, and for developers curious how a long-running engine reimplementation stays alive. The team sends you to GOG or the Ubisoft Store for the full game, which keeps the project on the right side of copyright. Fans of the sequel should look at VCMI, which does the same job for Heroes III. The catch is scope. This is not a game engine you build new games on. It exists to run one specific game, and without the original data files you only get the demo.

forge2.9k★

Forge is a full rules engine for Magic: The Gathering that runs on Windows, Mac, Linux, and Android for free. This is not a fan-made toy: it enforces the actual game rules across a massive card pool, with draft, sealed, Commander, cube, and a single-player adventure mode in the spirit of the old Shandalar game. Setup is download, install Java 17 or later, and run. The Android build sideloads and pulls its own assets on first launch. It's GPL-3.0 and community-built, unaffiliated with Wizards of the Coast, which is exactly why it can cover formats the official products never will. Use it to practice limited formats, test decks against an AI that doesn't embarrass itself, or play Commander offline. MTG Arena stays the polished official experience; Forge covers everything else. The catch is the obvious one: it lives in Wizards of the Coast's legal shadow and always has. The interface is functional rather than pretty, and the AI still misplays complex board states.

BRUTAL2.4k★

BRUTAL is the C# foundation RocketWerkz built Kitten Space Agency on, and the base Ludeon used for Waylith, the in-house engine moving RimWorld off Unity. It's a framework, not an engine: Vulkan, GLFW, SDL, Dear ImGui, Jolt and Box2D physics, FMOD audio and RakNet networking bindings, plus allocation-free collections, strings, memory and a job system. No editor, no scene graph, no renderer, by design. Free for commercial games, no royalties. Install from NuGet (dotnet add package Ahwoo.Brutal.Core) on .NET 10, with a Vulkan 1.3 GPU if you render. The README says Windows or Linux; the homepage also lists macOS. You can't build from source yet: project files and build scripts are "coming." Hello world opens an empty window. Everything after that, renderer included, is yours to write. There's no paid tier, but the license has a price: your credits, NOTICE.txt and the BRUTAL logo before gameplay, unless Ahwoo agrees otherwise. Solo devs: use Godot. Small studios with an engine programmer: worth a look. Larger studios outgrowing Unity: the real audience. The catch: it went public this month. Open issues already report missing native exports in the Box2D and Jolt bindings, and FMOD may need a separate Firelight license.

mtasa-blue1.9k★

Grand Theft Auto: San Andreas shipped in 2004 with no multiplayer at all. Multi Theft Auto (MTA) is the engine that makes that possible. It's a multiplayer mod framework that turns a 2004 single-player game into a platform for custom online experiences: racing, roleplay, zombie survival, whatever the server community builds. GPL v3, C++ core with Lua scripting for server-side game logic. The project has been active since the mid-2000s and still maintains an active player community. Servers run custom game modes written in Lua, and the modding API is extensive. You can alter nearly every game mechanic. Fully free. The mod client and server are free. You need a legitimate copy of GTA: San Andreas to play. Server hosting: run it on any machine or VPS. A small VPS ($5-10/mo) handles a decent player count. The Lua scripting API is well-documented and has a large library of community resources. The catch: this is a niche community project for a 20+ year old game. If you're not already in the GTA modding scene, this probably isn't for you. The codebase is old and complex. But for its community, MTA remains the most feature-rich multiplayer mod for San Andreas, beating the competing SA-MP (San Andreas Multiplayer) in scripting capabilities.

Tri-Inspector1.5k★

Tri Inspector makes Unity's inspector usable without paying for Odin. Add attributes to your fields and you get grouped and tabbed layouts, validation with inline error messages, conditional show and hide, buttons that call methods from the inspector, read-only fields, info boxes and reorderable table lists. It is the same category of quality-of-life work that makes designers stop asking engineers to change values for them. MIT licensed, distributed through OpenUPM. Nothing to run. Install the package from OpenUPM or a git URL and the attributes work. Version 2.0 is a preview release rebuilt on Unity's UI Toolkit, requiring Unity 6 or newer, with proper prefab override support so modified properties highlight, revert and apply correctly across prefab instances and variants. TableList rows are now drag-reorderable. If you need stability today, the 1.x branch is still there and still maintained. Free with no paid tier, which is the entire pitch given Odin Inspector sells for $55 per seat. Tri Inspector also integrates with Odin and Odin Validator rather than fighting them, so adopting it does not burn a bridge. Solo developers and small studios get most of Odin's daily value for nothing. The catch is that 2.0 is explicitly flagged as preview and may contain bugs, and it drops everything before Unity 6. Odin still wins on breadth, serialization of types Unity will not touch, and a support contract. Free covers the common cases, not all of them.

castle-engine1.3k★

Castle Engine is a cross-platform game engine with a visual editor, physics, scene graph, and support for glTF, X3D, and other 3D formats. It compiles to Windows, Linux, macOS, Android, iOS, and web via WebAssembly. LGPL-with-static-linking-exception (effectively permissive for games), Pascal. The visual editor handles scene composition, and you write game logic in Object Pascal. Built-in support for 2D and 3D, skeletal animation, shadows, shaders, and a component-based architecture similar to Unity's. Fully free. No paid tier, no asset store fees, no royalties. The engine and all tools are open source. Solo Pascal enthusiasts: this is your engine. Everyone else: look at Godot. The catch is obvious: Pascal. The game development world runs on C#, C++, GDScript, and Rust. The Castle Engine community is small, tutorials are limited, and hiring Pascal game developers is nearly impossible. If you already know and love Pascal, this is a genuine option. The engine is well-built and actively maintained. If you don't know Pascal, there's no compelling reason to choose this over Godot, which offers a similar indie-friendly, fully-free experience with a vastly larger community.

lightyear1.2k★

Multiplayer netcode is the part of game development that quietly kills projects. Lightyear handles it for the Bevy engine: server-authoritative networking for Rust games with client prediction, interpolation, and input handling built in, free and open source. It's a library, not a service, so there's no infrastructure beyond the game server you were already going to run. Transport is pluggable: UDP, WebSocket, WebTransport (which makes browser builds work), and Steam sockets. Inputs are buffered per tick and protected against packet loss, and there are first-class integrations with leafwing-input-manager and the Avian physics engine. Bevy developers building anything competitive or physics-heavy should start here instead of rolling their own. The main alternative in the same ecosystem is bevy_replicon, which is simpler but leaves prediction and interpolation to you. The catch: it moves with Bevy. Every engine release means a migration, the docs are a work-in-progress book, and outside Bevy it's useless to you by design.

ezyfox-server684★

EzyFox Server provides the plumbing. It supports TCP, UDP, and WebSocket protocols, so it works for mobile games, desktop games, and browser-based multiplayer. It's free under Apache 2.0. You get a socket server framework, plugin system, cluster support, and client SDKs for multiple platforms. The architecture is designed for real-time gaming scenarios: low-latency messaging, room-based matchmaking, and user authentication. The catch: this is a niche project with a small community. Documentation is limited and mostly example-driven. If you're evaluating real-time game servers, Colyseus (JavaScript) has a much larger community and better docs. Photon (proprietary) is the industry standard for commercial games. EzyFox fits if you specifically want Java and self-hosted, but you'll be figuring out edge cases on your own. The homepage URL pointing to star-history.com instead of actual project docs is not a confidence builder.