Python game template
Card, board & tiles making Software
Map and logic editor
Andruill Engine is a GMS (Game Management System) written in PHP.
A tools API for designing table top game utilities
An extensible game engine that targets RPGs.
CM Game Development Kit
Isometric engine for 2D rendering with XNA and SDL
A 2D Java game engine
A small Game Engine project.
The next generation mud is an open-source extensible, programmable mud