The Ren'Py Visual Novel Engine
A game engine powered by python and panda3d
A retro game engine for Python
Open source clone of the Age of Empires II engine
High performance UI layout library in C
Powerful, mature open-source cross-platform game engine for Python
3D game engine/framework in C, with Luajit and Python bindings now
Godot Minimal Theme
An OpenGL RTS game engine written in C
Cocos simplifies game creation and distribution with Cocos Creator
Cross-platform game engine in Rust
A game framework written with osu! in mind.
A .NET ascii/ansi console engine written in C# for MonoGame and XNA
3D and 2D game engine written in Rust
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Free, open source game engine online
A modern, cross-platform Quake game engine based on FitzQuake.
GemRB is a portable open-source implementation of the Infinity Engine
Game engine supporting many 3D/2D formats and graphic effects
PyCAPGE - Python Classic Adventure Point and Click Game Engine
API (C#) for simulating certain aspects of a ZX spectrum for porting.
A cell-based puzzle game featuring classic and completely new puzzles
Haskell game engine library for roguelike dungeon crawlers
Vivid3D is an open-source 3D engine with powerful 2D UI.