Self-hosted game stream host for Moonlight
Cooperative multiplayer graphical RPG and adventure game
Open source clone of the Age of Empires II engine
Powerful, mature open-source cross-platform game engine for Python
Code for Cicero, an AI agent that plays the game of Diplomacy
Source code repository of the FreeOrion project
A free/open source client and automation tool for Ragnarok Online
A game of dungeon exploration, combat and magic
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
GemRB is a portable open-source implementation of the Infinity Engine
Doom-based AI research platform for reinforcement learning
4X Space Strategy Game
Vivid3D is a C++ IDE/3D engine, with python scripting.
For exploring cellular automata like Conway's Game of Life.
2D Open Source MMORPG
Janken - A Simple Rock, Paper, Scissors Game
Updated emulator of Forgotten Realms: Unlimited Adventures
New Sabreman's adventure. New remake of a 80's game by igcefo
Procedurally-Generated Game-Like Gym-Environments
DOOM / Heretic / Hexen source port with enhanced graphics and UI
Pioneer, a space adventure game in the 31st Century Milky Way galaxy
KlayGE is a cross-platform open source game engine