The Tiny JavaScript Game Engine That Can!
Full featured MUD server with all the trimmings.
Haskell game engine library for roguelike dungeon crawlers
3D playground built on three.js and cannon.js
Planimeter Game Engine 2D - LÖVE-based game engine for Lua
A mobile game distributed server implemented using netty4.X
TurboSphere is an easy to learn and powerful JS based game engine.
Open source, moddable game engine for the "Polygon Love 2" game
Cross-platform 2D game engine