Visual Basic 6 2D online adventure game engine
Tools and Z80 engine for creating adventure games.
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Open source reimplementation of GTA San Andreas game engine in Unity
A hand-crafted 2D game library in Go
a UCI chess engine
Go 3D Game Engine
DOOM / Heretic / Hexen source port with enhanced graphics and UI
Cross-platform 3D scene editor based on three.js, golang and mongodb
SUMMARY
MHFPS Ported to the godot engine!
Vivid is a modern C++ 3D engine using OpenGL4+
RTSish Game Engine
Improved version of the X-Ray Engine, the game engine
Data-oriented and data-driven game engine written in Rust
Python ctypes module for the Irrlicht Engine SDK
2D Game Engine
3D Game engine with editor
mGSTEP port of the Cube game engine
3D playground built on three.js and cannon.js