RPG Maker 2000/2003 and EasyRPG games interpreter
HTML5 Phigros chart player/simulator
Aim assistance for blocks and mobs
Open-source rhythm game
Open-source Android/Desktop remake of Civ V
Archipelago Multi-Game Randomizer and Server
An open source re-implementation of RollerCoaster Tycoon 2
Doom-based AI research platform for reinforcement learning
One of the best Prodigy hacks
Voxel game-creation platform with easy modding and game creation
The Ren'Py Visual Novel Engine
The Oldschool Runescape API wrapper that does more
Endless Sky is a sandbox-style space exploration game
Fully async, multithreaded, predictive, open source, 3.01 reach
Classic overhead run-and-gun game
Access GameLift resources and integrate GameLift into your Unity game
A game of dungeon exploration, combat and magic
The Shiptest Codebase
You can make it - Open Source MMORPG Platform
Multi Theft Auto is a game engine
Minecraft map editor and mod
Free and open source real-time strategy game
The main repository for the development of the evolution game Thrive
Widelands is a free, open source real-time strategy game
3D space trading and combat game