Open-source alternatives to Halflife

Urho3D is a cross-platform 3D game engine written in C++. It uses a component-based scene graph to compose game objects from nodes and attached components, separating transforms from behaviors for modular design. The engine integrates AngelScript and Lua scripting for game logic, uses the Bullet library for physics simulation, and renders scenes with OpenGL or Direct3D through forward, deferred, or light pre-pass pipelines with customizable render passes and shadow mapping. The engine distinguishes itself with a built-in visual scene and UI editor for composing 3D worlds and interface layouts

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

Stride is a C# game engine and 3D rendering engine used for building three-dimensional games and virtual reality applications. It functions as a comprehensive framework and development kit for creating immersive experiences within a managed code environment. The project includes a developer GUI framework for building internal debugging tools and utility panels. It also serves as a 3D physics simulator for calculating rigid body dynamics and collision detection within a scene. The engine covers environmental scene rendering and project scaffolding workflows. It provides tooling for game devel

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

Fabric API is a modular framework designed for Minecraft mod development, providing a standardized set of hooks and libraries that enable the integration of custom content into the game. It serves as a foundational toolkit for injecting custom logic, assets, and networked data into the game environment during both startup and runtime phases. The framework distinguishes itself by facilitating interoperability between independent modifications through shared events and interface-based contracts, which allow different mods to interact without requiring direct dependencies. It manages the complex

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

Geode is a game modification SDK and mod loader for Geometry Dash. It functions as a hooking engine and UI framework that allows for the injection of dynamic libraries to alter game behavior and add new features. The toolkit distinguishes itself through a centralized mod compatibility manager and hook registry that tracks active modifications to prevent logic conflicts and application crashes. It utilizes a trampoline-based hooking engine to redirect game function calls while preserving native call stacks, alongside a dedicated UI framework for rendering custom popups and interface components

LumixEngine is a high-performance C++ 3D game engine designed for building interactive 3D applications. It is built on a data-oriented component system that organizes objects in contiguous memory blocks to maximize CPU cache performance. The engine features a dynamic binary plugin architecture for loading external modules at runtime and an embedded scripting virtual machine that exposes internal logic for external control without recompilation. Computational workloads are managed via a task-based parallel execution model that distributes jobs across multiple processor cores. The framework in

This repository contains the original source code for a classic real-time strategy game, serving as a legacy game engine implementation for managing units, maps, and combat mechanics in a military strategy setting. It functions as a real-time strategy game source code archive intended for preservation and technical study. The codebase acts as a game modification base, allowing developers to create custom content and modifications using the original source. It provides a foundation for retro game modding and software archeology to analyze how historical game mechanics were programmed. The pro

This project is a first-person shooter template for Unity that implements networked gameplay, weapon systems, and player traversal. It functions as a multiplayer system designed to synchronize movements and actions between a server and clients via a network transport layer. The project serves as an example of high-fidelity game rendering using the High Definition Render Pipeline to deliver authored content and advanced visual quality. It also demonstrates the use of an entity component system to organize game data and logic for optimized processing and execution performance. The implementati

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.

Mario-Kart-3.js is a browser-based 3D racing simulation implemented in JavaScript. It utilizes a WebGL game engine to render three-dimensional race tracks and vehicle models directly within a web browser using graphics hardware. The simulation features a physics-based drifting and maneuver system for gaining speed boosts and a power item system for deploying competitive advantages during races. The project encompasses a vehicle control system that maps keyboard and mouse inputs to steering and acceleration, alongside a simulation engine that manages collision detection and scripted item logi

Quake-2 is a game engine designed for the development of first-person shooters and the rendering of three-dimensional environments. It provides the core framework for processing real-time physics and player input within interactive 3D spaces. The engine supports software extensibility, allowing for the direct modification of source code to change gameplay mechanics and engine behaviors. This makes it a resource for retro game engineering and the study of early 3D development techniques. Its technical capabilities include vertex-based software rendering, BSP-tree spatial partitioning, and PVS

This is the original C source code for the Quake game engine, a landmark first-person shooter engine from the 1990s. It is a retro game engine that renders 3D environments and processes player input in real time using CPU-based software rendering rather than GPU acceleration. The engine supports networked multiplayer gameplay over LAN or internet connections and is designed to be moddable, allowing users to create and run custom game modifications and levels. The engine's architecture includes a Binary Space Partition tree for efficient world geometry organization and visibility determination

vcmi is an open-source game engine for Heroes of Might and Magic III that recreates the gameplay, logic, and rendering of the original strategy game. It serves as a cross-platform game runtime supporting Windows, Linux, macOS, Android, and iOS, providing a turn-based strategy simulator for strategic world map navigation and tactical combat. The project is built as a moddable game framework, featuring a data-driven modding system and a sandboxed Lua scripting integration. These allow for the definition of custom gameplay logic, spell effects, and the addition of new factions, characters, and a

OpenMW is a modern, open-source game engine designed to execute the game Morrowind and its expansions. It serves as a cross-platform game runtime and 3D world renderer, providing a data-driven environment to run game logic and physics with improved stability. The project functions as a game modding framework, utilizing a modular plugin system and an interpreted scripting layer to load external modifications. This architecture allows for the integration of community content, custom textures, and external scripts without altering the base executable code. The engine covers a broad range of cap

Source Engine is a cross-platform game engine designed for the development and execution of interactive three-dimensional applications. It provides a framework for rendering complex environments and managing multiplayer networking, functioning as a middleware solution for hosting independent game servers. The engine distinguishes itself through a client-server authoritative networking model that enables direct player connectivity without reliance on external authentication or matchmaking services. It utilizes a data-driven asset pipeline and a component-based entity system to decouple engine

NeoForge is a development framework and programming interface designed for modifying the Minecraft Java Edition game engine. It provides a standardized environment that allows developers to inject custom logic, extend core gameplay mechanics, and introduce new content into the game. The platform distinguishes itself by utilizing a system of hooks and registry patterns that manage how modifications interact with the game engine. It maintains stability across different versions by separating client and server execution environments and automating the discovery and loading of mod packages. The

This project is a cross-platform game engine framework and build pipeline designed to produce playable executable binaries for desktop and Android devices. It provides a collection of core libraries for game development, including a native Android build system and a C++ build pipeline. The framework features a specialized bitmap font rendering system that displays stylized typography by mapping character indices to image atlases using coordinate and spacing metadata. It also implements a hardware abstraction layer to decouple application logic from graphics and audio drivers, ensuring portabl

This project is a WebGL 3D game engine and comprehensive suite of tools for rendering high-performance 3D graphics and interactive scenes in the browser using WebGL and WebGPU. It provides a dedicated WebXR framework for building augmented and virtual reality experiences that run directly in a web browser. The engine includes a specialized Gaussian splatting renderer for displaying 3D point-cloud data to create photorealistic environmental captures. It utilizes a glTF asset pipeline to load and stream compressed 3D models and textures for efficient asset delivery. The system covers real-time

Ogre is a high-level 3D rendering engine designed for creating games, simulations, and visualizations without requiring low-level graphics API code. It functions as a framework for real-time 3D graphics processing, providing a physically based renderer to simulate lifelike surfaces and lighting. The engine includes specialized systems for skeletal animation to control character movement and a terrain generation system for producing large textured landscapes. These features are supported by automatic levels of detail and distance-based mesh management to maintain performance. The project cove

whs.js is a WebGL 3D game engine and extensible application framework used to create interactive 3D experiences and browser-based games. It provides a simplified abstraction layer over low-level WebGL rendering to manage cameras, lighting, and the overall 3D environment. The framework utilizes a modular 3D scene graph to organize objects into a hierarchical system of components. It integrates multithreaded physics simulation by using web workers to run calculations in parallel with the main render loop. The system includes a modular plugin architecture that allows for the extension of base a

jynew is a 3D RPG game engine and development framework designed for building three-dimensional role playing games. It provides a comprehensive suite of tools for scene editing, game logic scripting, and the creation of 3D environments. The project features a specialized 3D asset management pipeline for importing and aligning models and animations, including specific tools for weapon attachment and rendering. It includes a dedicated combat system editor for defining battle encounters, skill effects, and combat grids with real-time synchronization. Additionally, it provides a game modding fram

This project is a high-performance 3D game engine implementation written in C++. Its primary purpose centers on game engine development and retro game preservation, allowing for the study and compilation of original source code from a classic title. The engine utilizes a custom asset pipeline that integrates 3D models and scene data from Maya via a specialized export plugin. It is designed to be compiled across Windows, Linux, and macOS through a platform-specific build abstraction. Technical capabilities cover real-time OpenGL rendering, state-based game logic, and binary resource packaging

Ant is a modular game engine framework designed for building interactive 3D experiences. It provides a core runtime infrastructure that supports the integration of independent, reusable functional packages to extend engine capabilities. The engine features a specialized ahead-of-time asset pipeline that transforms raw 3D models, textures, and shaders into optimized binary formats. By utilizing pre-computed memory-mapped layouts, the system minimizes runtime processing overhead and improves loading speeds for game assets. Development is supported by a scriptable world editor that allows for s

Panda3D is a cross-platform game engine and 3D graphics rendering system developed for Python and C++. It functions as a comprehensive framework for building interactive 3D applications, providing a real-time physics simulator and a specialized 3D asset pipeline tool. The engine distinguishes itself by combining a high-performance C++ core with interoperable Python language bindings. It utilizes a scene graph architecture to organize 3D objects and provides a pipeline-based asset conversion system to optimize models and textures for runtime loading. Its capability surface includes low-level

This project is a browser-based game engine and implementation of a racing game built using a declarative component architecture. It provides a framework for constructing interactive three-dimensional environments and game objects by mapping hierarchical data structures to a persistent scene graph. The engine distinguishes itself by synchronizing game logic with high-performance rendering through a centralized data store. This approach ensures that physics calculations, player progress, and environmental variables remain consistent with the visual output of the scene. Developers can compose c