A very small multi-platform game engine for creating desktop games.
Open source, moddable game engine for the "Polygon Love 2" game
Java Client + JS/Canvas Server-Side System, with maintained Objects
WGFX 2D Game Engine
cross-platform 2d game engine
Point-and-click 2D game engine
Java game engine for shoot 'em ups, using Java2D.
A complete 2D Game Engine with built in drag and drop editor
RPG Games without coding!
A cross platform 3d c++ game engine
A 3D multiplayer RPG based in the world of Khoras.
A DirectX based graphics/physics engine
Opensource serious game engine for multiplayer games
The Lambda-Engine is a cross platform game engine.
Cross-platform 2D gaming middleware