The flexible game engine
Samples that demonstrate how to build graphics intensive applications
RPG Maker 2000/2003 and EasyRPG games interpreter
The source code to VVVVVV
2D game development library for Ruby and C++
Naev is a 2d action/rpg space game, action, rpg and simulation
Lightweight console for Minecraft chat and automated scripts
Cross-platform, open source, and super fast MUD client with scripting
A game framework written with osu! in mind.
A .NET ascii/ansi console engine written in C# for MonoGame and XNA
A dead simple 2D game library for Go
Cooperative multiplayer graphical RPG and adventure game
Action RPG that's easy to mod
Game engine to build text adventures.
GemRB is a portable open-source implementation of the Infinity Engine
A standalone UQM mod made to enhance gameplay and visuals
A cross-platform port of Hexen II game.
Final Fantasy VIII Save Editor
A promising chess program
INSTEAD - Simple Text Adventure Interpreter.
Cerberus Content Management System