Magic Another Game Engine
fheroes2 is a recreation of Heroes of Might and Magic II game engine
Fast and lightweight JavaScript game engine built on WebGL and glTF
2D game development library for Ruby and C++
Haskell game engine library for roguelike dungeon crawlers
A .NET ascii/ansi console engine written in C# for MonoGame and XNA
Embeddable unity game engine view for Flutter
Retro game engine for creating games like it's 1997
Opensource crossplatform Fallout 2 game engine writen in C++ and SDL
Game/Scene Development System
C++ lightweight cross-platform game engine
3D Scene Builder
A game engine for console based text games
A Tile-based Game Engine written in C# mimicing retro consoles.
Amateur 3D Game Engine
Vivid3D is an open-source 3D engine with powerful 2D UI.
Vivid is a modern C++ 3D engine using OpenGL4+
RTSish Game Engine
A cross-platform 2D game engine
Low-Level Game Engine for Retro Platforms
A tiny game engine to create arcade style 2D games.