Xash3D FWGS engine
The source code to VVVVVV
Open source cross-platform multi-purpose game toolkit
Cocos simplifies game creation and distribution with Cocos Creator
Fast and lightweight JavaScript game engine built on WebGL and glTF
Use the Delta Executor APK with Roblox on a Windows PC.
Source of Mana is a unique 2D MMORPG
Engo is an open-source 2D game engine written in Go
Open source script based on Master XLS
plugin-based RPG manager in C++ and Qt5
Cross-platform 2D game engine
Make games with Lego-like building blocks