An updated version of the classic "Basic Computer Games" book
Real Time Strategy game engine supporting early Westwood classics
A free/open source client and automation tool for Ragnarok Online
A lightweight online game framework
An open source implementation of the Ultima Online Classic Client
Free, open source game engine online
Play chess from your terminal
Tactical 2D shooter in fishy pixels style. Made with Rust-lang
Free Online MMORPG with Battlegrounds
Create custom themes for the Nintendo Switch
Open-source Android/Desktop remake of Civ V
The new All-in-One CFW package for the Nintendo Switch
Multi Theft Auto is a game engine
Free and open source real-time strategy game
Game Preservation Project
3D Game engine with editor
Magic Another Game Engine
Cross-platform, open source, and super fast MUD client with scripting
A game of dungeon exploration, combat and magic
Python MUD/MUX/MUSH/MU* development system
A downloadable game for Windows, macOS, and Linux
Online War system for IL-2 Sturmovik and Iron Front in ArmA 2
Free APK version of Garry's Mod, the Android sandbox physics game
A Universal Mod-Loader for Games built in the Unity Engine