DOOM / Heretic / Hexen source port with enhanced graphics and UI
3D C++ Game Engine - yet another open source game engine
Graphical hook for a D3D9-D3D12, OpenGL and Vulkan based games
Improved version of the X-Ray Engine, the game engine
DeSmuME is a Nintendo DS emulator
A mapping tool for text-based games like text adventures, MUDs, etc.
A 2D game engine and level editor
KlayGE is a cross-platform open source game engine
MAME Android Emulator.
Retro Games in Gym
A cross-platform 2D game engine
Character animation system for games and simulations.
Easy fine console input/output for java
Ubuntu-based Linux Gaming OS
Game backup loader for Wii and vWii
An End-To-End, Lightweight and Flexible Platform for Game Research
The event based Real-Time Operating System (RTOS) for Arduino
Several mods for Civilization IV: Colonization