Self-hosted game stream host for Moonlight
Open source clone of the Age of Empires II engine
Powerful, mature open-source cross-platform game engine for Python
A free/open source client and automation tool for Ragnarok Online
Source code repository of the FreeOrion project
Code for Cicero, an AI agent that plays the game of Diplomacy
Doom-based AI research platform for reinforcement learning
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
4X Space Strategy Game
Cooperative multiplayer graphical RPG and adventure game
GemRB is a portable open-source implementation of the Infinity Engine
Opensource Created Custom Viewers For Virtual Worlds like SecondLife.
For exploring cellular automata like Conway's Game of Life.
Realism Invictus mod for Civilization IV
Vivid3D is a C++ IDE/3D engine, with python scripting.
GameServer is a sophisticated, game server designed for online games
... the open-source glide computer
Janken - A Simple Rock, Paper, Scissors Game
Real-time collision detection and multi-physics simulation for VR
Procedurally-Generated Game-Like Gym-Environments