Phaser is a free and fast 2D game framework for making HTML5 games
Godot game template and component-based framework
3D game engine/framework in C, with Luajit and Python bindings now
UI Automation Framework for Games and Apps
Arianne is an engine to develop multiplayer online games like Stendhal
Sequential Workflow Designer is a lightweight workflow designer
JavaScript framework to build game engines, games, emulators and apps
Cerberus Content Management System
Open-source full-stack web development framework built on top of React
A Rust framework for building Minecraft servers
Building Local-First apps for Windows, MacOS, Linux, iOS and Android
Plugin pack for making 2D games with Bevy
Open-source, cross-platform, game-development tools
Build Cross-platform Applications
MMORPG
3D .NET engine for Windows, Linux, Mac
Make robots for MediaWiki-powered sites!
A Flash Molehill (Stage3D) GPU accelerated 2D game engine
The Flixel Power Tools are a set of plug-ins for Flixel 2.5+