Open-source alternatives to Spring

Openage is an open-source game engine designed to execute real-time strategy games. It provides the core logic, networking, and rendering infrastructure necessary to recreate classic strategy mechanics across multiple operating systems. The engine utilizes a deterministic lockstep simulation and a client-server architecture to maintain synchronized game states across participants. It distinguishes itself through a data-driven configuration system that allows for extensive game modding, enabling users to adjust mechanics and visual elements by editing human-readable files without requiring sou

Ambient is a cross-platform multiplayer game engine and runtime environment developed in Rust. It provides a system for building and deploying high-performance games that run across web browsers and desktop platforms using WebAssembly and WebGPU. The project features a networked database that automatically replicates real-time state and components between servers and players. It utilizes WebAssembly sandboxes to isolate game logic, which prevents individual script crashes and allows for the secure execution of untrusted code. The framework includes a graphics system for high-fidelity 3D visu

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

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

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 project is a real-time strategy game and military combat simulator focused on modern warfare. It provides a simulation where players build bases and command military units to achieve tactical objectives and execute combat operations across various global locations. The software functions as a user-generated content platform, featuring a community workshop for creating, uploading, and sharing custom maps. It also includes a narrative-driven single-player campaign consisting of a series of strategic missions. Gameplay involves battling computer-controlled commanders that utilize distinct

egret-core is a cross-platform game engine and mobile application framework used to develop 2D and 3D software for Android, iOS, and Windows. It serves as a multi-platform graphics engine and input handler designed to maintain consistent visual output and interaction behavior across different hardware. The project provides a game physics and animation suite that integrates external libraries for skeletal animations, particle systems, and complex physics simulations. It utilizes a hardware-abstraction layer to standardize touch, keyboard, and mouse interactions across multiple operating system

This project is a real-time strategy game framework built for the Godot engine, providing a foundational template for developing isometric strategy titles. It offers a collection of reusable systems designed to accelerate the creation of competitive games, including support for both human and artificial intelligence participants. The framework distinguishes itself through a comprehensive suite of core mechanics tailored for the real-time strategy genre. It includes a dedicated fog-of-war system that obscures map regions based on unit line-of-sight, alongside isometric pathfinding and navigati

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

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

This project is a real-time strategy game engine and a corresponding set of custom content toolkits. It provides a software framework for rendering 2D environments, executing gameplay logic, and managing the distribution of community-created assets. The system includes a dedicated game map editor for designing custom terrain and modifying game levels. It utilizes a data-driven map framework to store terrain data in structured files and employs an asset-based content distribution system to package these modifications for workshop integration. Gameplay consistency is maintained through a game

OpenRA is an open-source game engine designed for the development and modernization of real-time strategy titles. It provides a modular framework that allows developers to build standalone games or total conversion modifications by leveraging a trait-based entity composition system. The engine is built to support both the preservation of classic strategy games and the creation of new experiences, offering cross-platform compatibility and a flexible architecture for defining game rules and unit behaviors. The engine distinguishes itself through a configuration-driven approach where game logic,

OpenTTD is an open-source game engine and transport simulation game. It provides an isometric sandbox environment for building and managing complex logistics and transport networks. The project functions as a multiplayer simulation sandbox where users can build infrastructure cooperatively or competitively in a shared virtual world. The platform is designed as a moddable simulation system that supports external assets, graphics, and gameplay modifications. It includes mechanisms for downloading and integrating add-on content and utilizes a plugin-based system to extend game mechanics beyond t

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

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

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

Echo is a cross-platform game engine designed for the development of two-dimensional and three-dimensional interactive projects. It provides a unified environment that integrates scene management, visual scripting, and graphics rendering into a single workflow, allowing developers to build and deploy applications across desktop, mobile, and web platforms. The engine distinguishes itself through a node-based architecture that governs both scene organization and game logic. By utilizing a visual scripting tool and a data-flow shader graph, users can define complex behaviors and custom materials

React Native Game Engine is a framework for building 2D interactive experiences and simulations within mobile applications. It provides a dedicated controller for managing a fixed-step game loop, ensuring that game logic, user inputs, and state updates occur at a consistent frame rate. The engine utilizes an entity-component-system architecture to decouple game object data from behavior. By structuring objects as independent entities processed by reusable logic functions, it allows for the management of complex scenes through a centralized, data-driven approach. The framework supports the cr

OpenDiablo2 is an open-source re-implementation of an isometric action role-playing game engine. It functions as a cross-platform game client designed to execute core mechanics and logic across multiple operating systems using external game assets. The project focuses on recreating the functionality of a classic action RPG from the ground up through a community-driven effort. It provides a framework for running a game engine that simulates specific gameplay experiences and movement patterns. The engine includes capabilities for isometric projection rendering, deterministic game state simulat

tModLoader is a modding framework and toolset designed for expanding game content and extending core game logic. It provides a polymorphic content API that allows for the creation of new items, NPCs, projectiles, and world assets through object-oriented inheritance. The project is distinguished by its advanced code modification capabilities, utilizing intermediate language bytecode patching and reflection-based private access to alter internal game behavior. It features a hot-reloading assembly runtime that enables developers to recompile and apply source code changes in real-time without res

devilutionX is an open-source, cross-platform reimplementation of the original Diablo 1 game engine. It is a software framework designed to run the original action RPG logic and mechanics on modern operating systems by rewriting the engine in a current programming language. The project modernizes the legacy experience by adding support for widescreen resolutions, high-definition scaling, and configurable input mapping for various hardware controllers. It also introduces quality-of-life enhancements such as health bars, auto-loot, and tools to modify game speed and combat rules. The engine co

Nakama is a distributed server framework designed for real-time multiplayer games and social applications. It provides an authoritative runtime environment for executing game logic, ensuring consistent state and cheat-resistant gameplay across diverse client platforms. The system acts as a centralized backend, managing persistent player identities, social graphs, and real-time communication channels to support complex multiplayer interactions. The platform distinguishes itself through an integrated suite of LiveOps tools that allow developers to manage game economies, schedule time-bound even

This repository is a comprehensive collection of functional 2D and 3D demo projects and implementation samples for the Godot Game Engine. It serves as an interactive tutorial and reference library, providing a working codebase to demonstrate how to apply engine features in real-world scenarios. The collection focuses on practical implementation guides, covering a wide array of technical capabilities from basic engine fundamentals to advanced rendering and scripting techniques. It allows users to study the application of node-based composition, asset pipelines, and game logic through direct ex

Battle for Wesnoth is an open-source turn-based strategy game set in a high fantasy world, built around hex-grid tactical combat. At its core, it is both a complete game and a game engine, offering single-player campaigns and multiplayer battles where players command faction-specific units across terrain that provides tactical advantages. The project is fundamentally a turn-based strategy game with a dedicated multiplayer platform, supporting online and local matches with replay recording and playback. What distinguishes Wesnoth is its deep commitment to custom content creation and modding. T

Shattered Pixel Dungeon is an open-source roguelike dungeon crawler built as a turn-based strategy game. It features procedurally generated levels, hundreds of collectible items, and permadeath mechanics, all rendered from a single Java codebase that runs on Android, iOS, and desktop platforms. The game offers six distinct hero classes, each with branching subclass trees, endgame abilities, and talent points for deep character customization. Players battle over 60 enemy types, 30 traps, and 10 bosses across five dungeon regions, while managing equipment, enchantments, and alchemy-crafted gear

Serious Engine is an open-source framework designed for the development and execution of first-person shooter titles. It provides an integrated environment for rendering complex three-dimensional combat spaces and managing the core gameplay logic required for high-speed action sequences. The engine utilizes an entity-component-system architecture to manage game objects, supported by script-driven logic that allows for gameplay modifications without requiring engine recompilation. It distinguishes itself through a specialized rendering pipeline that separates geometry calculations from lightin

Beyond-All-Reason is a real-time strategy game and 3D military simulation focused on large-scale tactical combat, base building, and resource management. It functions as a competitive multiplayer platform featuring ranked lobbies and skill-based matchmaking. The project includes a custom map editor for designing unique game levels and environments through structural and thematic configuration. The simulation covers military-industrial economy management, including resource extraction and asset recovery. Tactical gameplay involves commanding army formations, using radar for enemy unit detecti