Lightweight console for Minecraft chat and automated scripts
Open source clone of the Age of Empires II engine
Self-hosted game stream host for Moonlight
A cross-platform PSP emulator
Rcon client for Minecraft
Set of Python modules designed for writing video games
Powerful, mature open-source cross-platform game engine for Python
One framework for creating powerful cross-platform games
A game engine powered by python and panda3d
The Ren'Py Visual Novel Engine
The ioquake3 community effort to continue supporting/developing id's
Xash3D FWGS engine
Mod manager for the video game RimWorld
An OpenGL RTS game engine written in C
A community sourced database of game controller mappings
A free/open source client and automation tool for Ragnarok Online
Source code repository of the FreeOrion project
An open source flight dynamics & control software library
Injectable LUA scripting system, SDK generator, live property editor
TGMC: TerraGov Marine Corps, a SS13 mod
Doom-based AI research platform for reinforcement learning
Free game engine for development of desktop, mobile, and web games
A dead simple 2D game engine for Go
Free, open source game engine online