Open-source alternatives to Quake

Spring is a cross-platform game engine and framework designed specifically for the development and execution of multiplayer real-time strategy games. It provides a high-performance simulation environment for managing large-scale battles and unit movements across different operating systems using a shared codebase. The engine functions as a multiplayer game server and networking layer, coordinating real-time game state and match synchronization between remote players. It includes a dedicated lobby client system for multiplayer match coordination as well as the capability to execute single-play

Quake III Arena is a first-person shooter game engine and arena combat simulator. It consists of the original C++ game source code for a cross-platform 3D game designed to run on Windows, Linux, and Mac. The project provides the source code necessary to render a first-person shooter experience, focusing on player-versus-player battles in closed 3D environments. It serves as a resource for legacy game preservation and the study of early 3D game engine construction. The engine incorporates spatial partitioning, client-side prediction, and state synchronization to manage multiplayer networking

The original open source release of Wolfenstein 3D

TIC-80 is a fantasy console platform and multi-language game engine that provides a virtual retro game development environment. It operates via a bytecode virtual machine that executes game logic within fixed memory and resolution constraints. The project distinguishes itself by offering integrated asset editors for pixel art, tile maps, and a pattern-based chiptune audio workstation all within a single environment. It supports multi-language scripting, allowing developers to write logic in Lua, JavaScript, or Ruby, and provides a standalone game exporter to package projects into native execu

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

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

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

Craft is a multiplayer voxel sandbox written in C. It utilizes an OpenGL voxel engine to render a block-based world and implements an infinite terrain generator that uses noise functions to create deterministic, procedural landscapes. The project features a networked environment where players can build and modify a shared world using socket-based state synchronization. To maintain consistency across sessions, it employs a voxel world database to store and retrieve modified block coordinates. The system covers a range of capabilities including 3D collision detection for character movement, to

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

Veloren is an open-source multiplayer RPG featuring a voxel-based action adventure in a procedurally generated fantasy world. It is built upon a voxel game engine that supports 3D rendering via Vulkan and Metal, utilizing a procedural world generator to create geography and ecosystems based on erosion algorithms and temperature maps. The project is distinguished by a sandboxed plugin system using WebAssembly, which allows for the addition of new game logic and equipment without recompiling the core engine. It also features a dedicated game server architecture designed to synchronize state, ma

Unciv is an open-source, cross-platform turn-based strategy game and a community-driven remake of a commercial strategy title. It simulates empire building, city management, and technological research for players on Android and desktop platforms. The project is designed as a moddable game engine, allowing users to override gameplay rules, modify units and buildings via external definition files, and replace audiovisual assets. It supports the distribution of custom maps and the ability to import mod archives from remote web addresses. The application includes a dedicated server for multiplay

The GoldSrc game engine is a 3D game framework and first-person shooter engine designed for building and running interactive software. It functions as a moddable game framework, providing a system for creating custom game rules and content through client-side code and shared libraries. The project includes a game engine SDK and development tools for compiling custom game logic into dynamic link libraries. This modular structure allows for the development and distribution of game modifications on Windows and Linux platforms.

Onion is a custom handheld gaming operating system and retro gaming frontend designed to manage and launch emulators on portable hardware. It functions as a bootable custom firmware distribution and emulation environment manager that replaces factory software to provide an integrated gaming environment. The system distinguishes itself through a modular core-based emulation architecture, allowing for the installation of verified emulator packages, BIOS configuration, and the use of hardware-specific drivers and filters. It also supports the integration of third-party game ports via standardize

BrowserQuest is a WebSocket multiplayer game engine and real-time state synchronization tool. It functions as a web-based game server designed to manage concurrent connections and broadcast updates to maintain a consistent shared world state between a central server and distributed web clients. The project enables real-time multiplayer gaming and browser-based game development by implementing low-latency data exchange. It focuses on game state synchronization to ensure that multiple players interacting within the same environment see the same actions and world states simultaneously. The syst

MAME is a vintage hardware emulation platform designed to recreate the circuitry of arcade games, computers, and consoles to run original software on modern devices. It functions as a retro gaming preservation framework for managing, verifying, and archiving ROM sets and disk images to ensure long-term software accessibility. The project features a system debugging tool for inspecting emulated memory, CPU registers, and execution flow via breakpoints and disassembly. It also includes a Lua-based automation layer that exposes core system state and hardware controls for custom behavior and anal

RetroArch is a cross-platform emulation host and multi-system game emulator that serves as a frontend for the Libretro API. It coordinates video, audio, and user input to maintain the application state for various emulator cores, allowing it to run a wide variety of vintage gaming hardware and software engines. The platform distinguishes itself through a low-latency emulation model that uses run-ahead processing to reduce input lag. It also features a real-time state tracking system that enables gameplay rewinding by saving periodic snapshots of the emulator memory state. The environment inc

Automatically exported from code.google.com/p/micropolis

Doom 3 GPL source release

This project is a 6502 assembly language implementation of a platformer featuring running, jumping, and swordfighting, developed for the Apple II computer between 1985 and 1989. It serves as a piece of legacy retro gaming software designed to run on 8-bit hardware from the early computing era. The repository provides the assembly source code for the purpose of historical technical analysis and research. It allows for the study of original game source to perform technical analysis and historical research into early video games. The project covers domains including 6502 assembly programming, A

Pure C Game Engine

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This project is a browser-based, real-time multiplayer action game where players control a character on a 2D canvas to absorb objects and grow in size. It utilizes a Node.js game server and WebSockets to synchronize game state, player movement, and chat across all connected participants. The application is delivered as a dockerized game application, ensuring consistent hosting and deployment across different cloud environments through containerized server environments. The system implements an authoritative server model that processes all game logic and physics to prevent cheating and mainta

KBEngine is a distributed game server engine and backend infrastructure designed for massively multiplayer online environments. It provides a multi-process architecture to handle high player concurrency and real-time interactions within a shared virtual world. The system features a scriptable game logic framework that combines a high-performance core with a high-level scripting language. This allows for game behavior modifications through a hot-fixable runtime that updates logic without requiring server restarts. The engine manages server scaling via dynamic load balancing across multiple ha

Paper is a high-performance server implementation for hosting multiplayer Minecraft games. It functions as a performance-oriented game engine designed to reduce resource usage and resolve mechanical inconsistencies in game logic. The project provides a platform for extending server logic and adding custom gameplay features through a dedicated plugin API. This allows for the development and integration of third-party extensions to add specialized capabilities to the server environment. The software covers several technical areas including server performance optimization for high-concurrency e

Space Station 14 is a C# multiplayer game and roleplay simulation framework. It is built upon an Entity-Component-System (ECS) game engine that separates logic into systems and data into components to manage complex entity interactions. The project functions as a grid-based physics simulator with a YAML data-driven prototype system for defining game objects. The project features a specialized 2D sprite rendering engine that maps server-side appearance data to client-side shaders. It implements a networking model with client-side prediction and dirty-flagged state synchronization to reduce inp

Cuberite is a high-performance multiplayer game server for Java Edition clients, designed to provide a low-memory and low-CPU environment for hosting shared virtual spaces. The server is built for cross-platform deployment across various operating systems and hardware types. It allows for the extension of game mechanics and server logic through a Lua scripting interface, enabling functionality changes without recompiling the core engine. The project includes tools for server administration via a remote console and world data management for analyzing statistics and optimizing save file storag

Pomelo is a distributed Node.js game server framework designed for building scalable multiplayer game backends and real-time web applications. It employs a multi-process architecture to distribute application logic horizontally across a cluster of machines, enabling high concurrency and balanced network traffic. The framework utilizes a WebSocket communication layer to manage bidirectional data exchange between diverse web clients and server clusters. It incorporates a remote procedure call system for triggering functions across remote server processes and uses Protocol Buffers for binary ser