Open-source alternatives to Halley

Amethyst is a data-driven game engine written in Rust for building high-performance 2D and 3D games. It is built on an entity component system architecture that decouples game state from logic to enable parallel processing and reusable code. The framework features a glTF 3D renderer for importing scenes and geometry using physically based materials. It also serves as a multiplayer game framework, providing network transport abstractions and state synchronization for real-time online experiences. The engine covers a broad range of capabilities, including hybrid 2D/3D rendering, asynchronous a

The Source Engine SDK is a C++ game development kit and modding framework designed for creating game modifications and custom gameplay extensions for the Source engine. It provides a structured environment and a collection of source code and binaries required to build custom content for compatible titles. The kit serves as a toolset for C++ game engine programming, enabling the development of custom gameplay mechanics, new rulesets, and game modes. It includes the libraries and headers necessary to compile and build gameplay extensions and custom game content.

Defold is a cross-platform game engine and integrated development environment used to create 2D and 3D games for desktop, mobile, and web targets. It combines a game development IDE for asset and scene management with a multi-platform build system and a scripting environment based on Lua. The engine includes a specialized headless runtime for hosting game servers and performing automated testing without a graphical interface. It supports native engine extensions, allowing custom low-level code to be integrated into the core to expand functionality beyond the standard scripting interface. The

MonoGame is a cross-platform game framework and C# game engine designed for the development of interactive software. It provides a unified environment for building games that run across desktop, mobile, and console platforms using a single codebase. The framework functions as a 2D graphics rendering library, offering tools to apply custom shaders and visual effects to game assets. It utilizes a graphics abstraction layer to map drawing commands to platform-specific APIs, ensuring consistent rendering across diverse hardware. The engine manages hardware-level tasks such as input handling, aud

Gameplay is a high-performance C++ game engine and cross-platform framework designed for developing 2D and 3D interactive games. It functions as both a 3D graphics engine for rendering environments and a 2D game development kit for creating sprite-based mechanics. The framework provides a cross-platform abstraction layer to ensure that game logic and graphics run across various hardware and software platforms using a shared codebase. The engine implements a hardware-accelerated rendering pipeline and component-based game logic to separate data from behavior. It utilizes a native C++ impleme

This project is an open-source 3D game engine designed for building high-fidelity games, simulations, and cinematic environments. It functions as a robotics simulation platform with native integration for ROS 2 to model robot controllers and sensors. The engine features a multi-threaded Forward+ physically based renderer that supports hardware-accelerated ray tracing and global illumination. The system is built on a modular extension architecture using Gems to add or replace features without modifying core binaries. It includes a native SDK for AWS cloud integration, enabling IAM authenticati

Turbulenz Engine is a cross-platform game engine and HTML5 framework designed for rendering graphics and simulating physics across desktop, mobile, and web environments. It functions as a WebGL graphics engine and a web-based physics engine, providing the necessary tools to build 2D and 3D games that run within browsers. The project includes a real-time multiplayer framework that synchronizes game states and player interactions between multiple users via server-side communication. This allows for the coordination of both real-time and asynchronous turn-based actions to maintain a consistent s

Magnum is a C++ middleware suite for cross-platform graphics development and real-time data visualization. It provides a hardware-agnostic rendering layer that translates graphics commands into platform-specific calls, ensuring consistent behavior across different GPU drivers and APIs such as Vulkan. The project focuses on decoupling application logic from underlying hardware through abstract graphics and system utilities. It features a plugin-based resource importer for 3D assets and audio, a hierarchical scene graph for spatial transformations, and a high-performance signal-based event syst

Cocos Engine is a cross-platform game engine designed for building high-performance 2D and 3D interactive experiences for web, mobile, and desktop platforms. It features a multi-backend rendering engine and a 2D and 3D physics simulator, utilizing a core architecture that combines a C++ runtime for performance with TypeScript for game logic scripting. The engine distinguishes itself through a multi-platform deployment system that packages projects for native operating systems and instant-play web ecosystems. Its graphics system supports multiple APIs, employing physically based rendering and

Shipwright is a native execution engine designed to run decompiled legacy game code on modern hardware. It functions as a game engine execution layer that provides a high-performance environment for legacy logic while ensuring compatibility with current systems. The project features a pluggable graphics API wrapper that allows for switching between different rendering backends to ensure visual stability across various operating systems. It also includes a custom asset loader that imports external archive files to modify game content and add custom assets. Additional capabilities include an i

This project is a cross-platform graphics wrapper and translation layer that implements the OpenGL ES and EGL specifications. It functions as a graphics API bridge, mapping OpenGL ES calls and WebGL content to platform-specific hardware APIs such as Vulkan and Metal to ensure consistent rendering across different operating systems. The system features a shader translation service that validates shading language code and transpiles it into multiple target languages, including HLSL, SPIR-V, and Metal SL. It employs a pluggable backend architecture to select the appropriate hardware rendering AP

This repository provides the source code for the Unity game engine, serving as a reference for the internal implementation of its core systems and managed scripting environment. It functions as a development resource for understanding how high-level C# logic interacts with the underlying engine architecture to build interactive 2D and 3D applications. By providing visibility into the engine's source files, this project enables developers to inspect execution flows and trace implementation details. This transparency supports the troubleshooting of complex behaviors and the analysis of how spec

This project is a cross-platform game engine and development toolkit designed for creating high-performance 2D and 3D games. It serves as a 3D graphics rendering engine and a web-based game framework that allows applications to be deployed across mobile, desktop, and web environments from a single codebase. The engine features a configurable render pipeline that supports both forward and deferred rendering paths. It utilizes a cross-platform graphics abstraction layer and universal shader translation to ensure consistent visual output across different hardware and platforms. The toolkit incl

Ebiten is a cross-platform 2D game engine and framework for the Go programming language. It provides a hardware-accelerated 2D renderer and a multi-input handling library to develop two-dimensional games with a single codebase. The engine is designed for broad deployment, allowing applications to be compiled and run across desktops, mobile devices, web browsers, and gaming consoles. It distinguishes itself by integrating custom shader programming for specialized visual effects and providing haptic feedback control for mobile devices and gamepads. The framework covers core game development ca

This repository contains the C++ game source code for a single-player first-person shooter action game. It is a software implementation of the Id Tech 4 engine, designed for 3D rendering with a focus on real-time unified lighting and geometry. The project enables the modification of core engine logic and rendering systems. It serves as a resource for classic game engine modification, first-person shooter development, and retro game preservation. The engine utilizes a unified shader pipeline and stencil shadow volumes for lighting effects, alongside BSP tree spatial partitioning for visibilit

This project provides a foundational template and boilerplate structure for developing games with the Bevy engine in Rust. It is designed to facilitate cross-platform development by offering a unified codebase that targets desktop, mobile, and web environments. The template distinguishes itself through pre-configured automation pipelines that handle the complexities of multi-platform build orchestration. It includes integrated workflows for continuous integration, allowing developers to validate code compatibility and stability across various operating systems and hardware architectures autom

The Forge is a low-level toolkit for building high-performance graphics engines and applications across desktop, mobile, and console platforms. It provides a cross-platform engine framework and a dedicated shader compiler that translates a single source into target-specific languages for various graphics APIs and hardware. The project includes a GPU memory and resource manager that utilizes unified root signatures for resource binding, alongside a ray tracing rendering pipeline that implements hardware-accelerated ray and path tracing queries. State management is handled through a high-perfor

Filament is a real-time physically based rendering engine designed for high-fidelity 3D graphics. It functions as a cross-platform graphics library that provides a unified interface for rendering complex models and materials across desktop, mobile, and web environments. The engine distinguishes itself through a data-oriented architecture that optimizes memory usage and processing speed, alongside a shader-variant system that generates specialized code for specific material and lighting configurations. By abstracting diverse hardware graphics backends, it ensures consistent visual performance

Ren'Py is a cross-platform game engine and interactive storytelling tool built around a Python-based scripting engine. It is designed for creating visual novels and branching narrative games, where player choices determine story paths and character interactions. The engine provides a complete development framework for building narrative-driven experiences, from simple dialogue trees to complex life simulation games. The engine distinguishes itself through a comprehensive set of integrated systems that handle the full lifecycle of interactive storytelling. Its script-based story engine compile

DiligentEngine is a cross-platform graphics abstraction layer and physically-based rendering engine. It provides a unified interface for executing 3D graphics commands across multiple low-level rendering backends from a single codebase, including a dedicated system for importing 3D assets via the GLTF 2.0 format. The engine features an HLSL shader cross-compiler that allows a single set of shaders to run across different graphics APIs and operating systems. It supports advanced rendering capabilities such as ray-tracing, mesh shaders, variable rate shading, and bindless resources. The framew

Liteflow is a component-based rule engine and workflow orchestrator used to define business logic through a chain of reusable components. It utilizes a structured data language to map logic paths, functioning as a dynamic workflow engine for managing sequences of synchronous and asynchronous tasks. The project is distinguished by its support for hot deployment, allowing rule definitions and execution logic to be updated in real time without restarting the application. It also features a multi-language scripting engine that embeds external scripts into business rules to enable flexible logic c

EnTT is a C++ library designed for data-oriented design and entity component system architecture. It provides a framework for managing game objects and simulation states by separating entity data from logic, allowing for the efficient organization and manipulation of large collections of related data objects. The library utilizes sparse sets to store entities and components in contiguous memory, which facilitates cache-friendly iteration and constant-time lookups. It employs template metaprogramming for compile-time type reflection and type-erasure techniques to provide a unified interface fo

Bevy is a cross-platform game engine and framework built in Rust, designed for creating interactive simulations and graphical applications. It utilizes a data-oriented entity-component-system architecture to manage game state, organizing data into contiguous memory blocks to facilitate high-performance processing and massive parallelization of entities. The engine distinguishes itself through a modular plugin architecture and a system-based task scheduler that automatically parallelizes logic by analyzing data access patterns. By employing reactive change detection and deferred command buffer

Padrino is a full-stack web application framework that extends Sinatra to build modular applications. It provides a structured environment for organizing URL endpoints into hierarchical controllers with named route aliases, dynamic parameters, and custom request lifecycle filters. Developers can combine multiple independent web sub-applications into a single running instance with isolated routing and configuration. The framework includes command-line automation tools for project generation, controller and action scaffolding, database model creation, and database migration generation. It featu

Fyrox is a Rust-based game engine for building both 2D and 3D games, designed as a native engine with no runtime dependencies. It compiles directly to native code for Windows, macOS, Linux, and WebAssembly, providing direct hardware access through the Rust programming language. The engine is built around an entity-component-system architecture that organizes game objects as entities with attached components processed by modular systems. Its graph-based scene management represents game scenes as directed acyclic graphs of nodes with transform hierarchies and property inheritance, while a paral

This is a web-based 3D game engine designed for creating high-performance interactive experiences on web and mobile platforms. It functions as a real-time graphics renderer and physics engine, utilizing a component-based scene graph to organize entities and their properties for three-dimensional rendering. The engine includes a visual scene editor that allows for the design of environments through a graphical interface, which then exports these assets as executable code. Its broader capabilities cover real-time graphics rendering for 2D and 3D elements, physical world simulation for object c

FlaxEngine is a cross-platform game engine and development kit designed for creating high-fidelity 2D and 3D games. It functions as a programmable framework that supports the use of C# and C++ for building interactive experiences. The project includes a high-speed graphics rendering engine capable of producing professional visual assets and detailed three-dimensional scenes. It provides a pipeline for compiling and exporting project files across various operating systems using native software development kits and toolchains.