Open-source alternatives to Ppy Osu

NATS Server is a high-performance, lightweight messaging system designed for cloud-native applications, edge computing, and distributed microservices. It functions as a distributed publish-subscribe broker that routes messages using hierarchical, dot-separated subject strings, enabling decoupled communication between services without requiring centralized broker lookups. The system supports core messaging patterns including asynchronous publish-subscribe, request-reply, and load-balanced queue processing. The platform distinguishes itself through a decentralized architecture that eliminates t

KMP-Awesome is a curated directory and resource index for the Kotlin Multiplatform ecosystem. It serves as a centralized hub for developers to discover libraries, frameworks, and tools designed to streamline the creation of shared codebases for mobile, desktop, and web applications. The project distinguishes itself by organizing a comprehensive collection of solutions that address the core challenges of cross-platform development. It highlights resources for implementing shared business logic, declarative user interface components, and type-safe data persistence layers. By providing a structu

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

Piccolo is a mini game engine designed for building small-scale games with cross-platform support. It compiles and runs on Windows, macOS, and Linux from a unified codebase, and includes an editor integration for live editing and debugging. The engine uses a component-based entity system with data-oriented design, storing component data in contiguous arrays for cache-friendly iteration. It features a fixed timestep game loop that decouples simulation updates from rendering frame rate, and provides a physics debug overlay that renders visual shapes from simulation data synchronized with the ed

Endless Sky is an open-source space trading simulation, 2D space combat simulator, and narrative exploration game. It functions as a plugin-based game engine that allows users to explore a vast universe, engage in tactical ship battles, and progress through a central plot within a sandbox environment. The project is distinguished by its highly moddable architecture, utilizing a directory-based plugin system and data-driven entity definitions to allow for content extensions and behavior overrides without recompiling source code. It further supports visual customization through programmable ver

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

Funkin is a rhythm game engine and scriptable gameplay framework designed for creating musical battle games with synchronized note charts and audio. It functions as a comprehensive toolset for rhythm game modding, allowing for the addition of custom songs, characters, and stages through external assets and metadata. The project distinguishes itself through a dedicated modding system that supports priority-based asset overriding and a data patching utility for modifying JSON and XML configuration files via targeted merge operations. It utilizes a scriptable environment that executes external s

Hazel is a C++ game development framework and 3D graphics rendering engine designed for building high-performance interactive software. It provides a foundational architecture that enables the construction of desktop applications through native hardware acceleration. The project includes a dedicated game engine editor that allows for the design and testing of interactive 3D and 2D scenes within a unified environment. This editor utilizes an immediate mode interface to maintain synchronization with the engine state, while a hardware-agnostic abstraction layer handles rendering commands across

CorsixTH is an open-source game clone and hospital management simulation game. It functions as a reproduction of a classic management title where players coordinate staff and treat patients to manage a medical facility. The project includes a level editor tool for designing original maps and campaigns. It also features a customizable input system that allows users to map game hotkeys and personalize control schemes. The simulation supports game localization to translate interface text and dialogue into multiple languages.

Cocos2d-x is a high-performance C++ game development framework designed for building and deploying interactive applications across mobile, desktop, and web platforms. It functions as a cross-platform game engine that utilizes an entity-component system to manage object lifecycles, behaviors, and spatial relationships within a unified codebase. The engine is distinguished by its specialized 2D graphics rendering pipeline, which is optimized for hardware-accelerated performance when displaying sprites, particle effects, and skeletal animations. It provides developers with low-level access to gr

Luanti is an open-source sandbox game engine designed for the creation and exploration of interactive three-dimensional voxel environments. It functions as a platform for building persistent digital spaces where users can modify block-based worlds and share custom content. The engine provides a framework for multiplayer interaction, utilizing a client-server architecture to synchronize world states across connected participants. It incorporates a scripting interface that allows for the integration of user-created modifications, alongside a centralized distribution system for managing and inst

Minetest is an open-source voxel game engine and platform used to create and share moddable 3D block-based games. It provides a framework for building interactive grid environments and generating custom voxel worlds. The project features a Lua-based modding framework that allows for the extension of game behavior and the addition of custom content without altering the core engine. This data-driven system supports a dedicated workflow for modifying game environments and logic. The engine supports multiplayer game hosting through a dedicated server architecture, enabling multiple players to co

Lila is a comprehensive, open-source chess gaming platform designed for real-time multiplayer interaction, competitive tournament management, and deep strategic analysis. It provides a global environment where users can engage in live matches, participate in structured competitions, and access extensive archives of historical game data for research and study. The platform distinguishes itself through a highly scalable architecture that utilizes actor-model concurrency and event-sourced game states to ensure precise match reconstruction and fault tolerance. It integrates distributed engine eva

ieaseMusic is a third-party desktop client for streaming and managing music from the NetEase Cloud Music service. It functions as a lossless audio player capable of streaming high-fidelity tracks to ensure sound quality. The application includes a music download manager for archiving tracks to a local device for offline use and a music activity sync tool that synchronizes listening history with external monitoring services. It utilizes a fallback system to resolve broken links by fetching audio from alternative providers. The client features QR code authentication for account access and prov

FreeScout is a self-hosted, open-source help desk and ticket management system built with PHP. It functions as a customer support platform that enables teams to manage shared inboxes and organize customer email conversations into tickets. The platform distinguishes itself as a multi-channel support dashboard that integrates customer relationship management and a knowledge base system. It provides tools for tracking detailed customer profiles and organizational records while offering a programmable interface to manage and expose support articles. The system covers a broad range of support cap

Automatisch is an open-source, self-hosted automation platform designed to orchestrate multi-stage workflows across various third-party web services. It functions as a no-code integration engine that allows users to connect disparate applications, enabling the automated movement of data and the execution of tasks without manual intervention. By running the platform on private infrastructure, users maintain full control over their data and ensure compliance with internal security policies. The platform distinguishes itself through a focus on secure, local credential management and flexible int

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 project is a Node.js web application boilerplate designed to accelerate development by providing a pre-configured foundation with integrated routing, templating, and developer tooling. It serves as a comprehensive starter kit that includes a full-stack authentication system, a payment integration starter, and an LLM agent framework. The framework distinguishes itself with specialized tools for AI development, including a retrieval-augmented generation implementation kit with vector search and semantic caching. It enables the creation of reasoning agents featuring tool-calling loops and r

This project is a .NET Core content management system and multi-site management platform designed to organize and publish structured digital content across independent websites from a centralized interface. It functions as both a headless CMS and a static site generator, rendering dynamic templates into HTML files to increase loading speed and scalability. The system integrates retrieval-augmented generation to transform website documents and content into searchable AI knowledge bases. It includes a visual AI workflow orchestrator to define the logic between user queries and large language mo

picacg-qt is a cross-platform desktop client for browsing and reading digital manga and comics from remote services. It provides a dedicated interface for navigating remote libraries, searching for specific titles, and viewing media content on Windows, Linux, and MacOS. The application includes an integrated artificial intelligence tool to upscale the resolution and visual quality of comic images. It also functions as an offline downloader, allowing users to archive comic sets and images from remote providers to local storage. The system handles asynchronous media downloading and local image

This application is a cross-platform desktop utility designed for automated translation, optical character recognition, and speech synthesis. It functions as a modular client that integrates various local and remote language services, allowing users to process text through hotkeys, clipboard monitoring, or direct input. The software distinguishes itself through a plugin-based architecture and a built-in automation framework. By exposing a local network interface, it enables external applications and scripts to programmatically trigger its translation and recognition workflows. Users can furth

Pyvideotrans is an automated video localization platform designed to transcribe, translate, and dub media content for international distribution. It functions as an end-to-end workflow that combines speech recognition, text translation, and synthetic voice generation to process video files into localized versions. The system distinguishes itself by offering a choice between local model inference for privacy and integration with third-party cloud services via user-provided credentials. This architecture allows users to maintain control over their billing and data security while utilizing modul

HMCL is a JVM-based cross-platform utility and Minecraft game launcher designed to install, manage, and launch multiple versions of Minecraft. It functions as an instance manager for organizing separate game profiles with unique settings and assets, as well as a mod loader manager for automating the installation of modification frameworks and community-created content. The project features a modular UI framework with a pluggable layout system, decoupling the visual interface from the core logic to allow for appearance and arrangement customizations. It automates the integration of modificatio

NewsBlur is an RSS feed aggregator and social news reader that collects and organizes stories from feeds, newsletters, and websites into a single interface. It functions as a feed synchronization service that maintains read states and subscription data across multiple devices and third-party applications. The platform distinguishes itself with AI-powered content summarization to generate briefings and answer questions about articles, alongside a system for training content classifiers. These classifiers learn user preferences for authors and tags to automatically highlight preferred topics or

This project is a web-based collaborative editor and scientific document management system designed for LaTeX. It provides a centralized environment for writing, editing, and compiling academic manuscripts, enabling multiple users to work on the same project simultaneously through real-time synchronization. The platform distinguishes itself by treating documents as version-controlled repositories, allowing for granular history tracking and bidirectional synchronization with external version control systems. It features a secure, containerized compilation pipeline that isolates build processes

Grav is a flat-file content management system that eliminates the need for a traditional database by storing site content and configuration in human-readable Markdown and YAML files. Built as a modular PHP web framework, it uses a hierarchical page routing system where the physical directory structure directly determines the site's URL paths. The platform is distinguished by its event-driven plugin architecture and a command-line interface that prioritizes system administration, deployment, and maintenance tasks. It utilizes a blueprint-driven system to generate administrative forms from stru

This project is a comprehensive zero-knowledge security suite designed for enterprise credential management, secrets orchestration, and password management. It provides a secure, end-to-end encrypted vault that allows users to store, synchronize, and manage sensitive information, including passwords, passkeys, and infrastructure secrets, across desktop, mobile, and browser environments. The platform distinguishes itself through a strict zero-knowledge architecture where all encryption and decryption occur locally on the client, ensuring that plaintext data remains inaccessible to the server.