fheroes2 is a recreation of Heroes of Might and Magic II game engine
Go bindings for raylib, a simple and easy-to-use library
3D and 2D game engine written in Rust
GemRB is a portable open-source implementation of the Infinity Engine
Game engine supporting many 3D/2D formats and graphic effects
Full featured MUD server with all the trimmings.
Ze Text Adventure game Builder : Create as you play !
utility collection for 2D game development in Java; sound-player
An isometric arcade-style game of skill, puzzles and exploration
Orx: Data-Driven Game Engine
PyCAPGE - Python Classic Adventure Point and Click Game Engine
The world is no longer the same
Amateur 3D Game Engine
C++ lightweight cross-platform game engine
RTSish Game Engine
ZDoom 2.8.1 fork focusing on modernisation, performance and stability
Vivid3D is an open-source 3D engine with powerful 2D UI.
A fork of Chocolate Doom with small Quality of Life enhancements
A fork of dhewm3 with an emphasis on modernisation and vanilla Doom 3
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Vivid is a modern C++ 3D engine using OpenGL4+