Epiar is a space adventure/combat game where you begin as a shuttle pilot in a galaxy generally ruled by anarchy, with few stable governments and numerous rebel factions. You start your adventure off doing whatever you want, but generally trying to save up money for a new starship, your adventure taking off from there.
ErisMUD is a MUD/MOO server/engine written in Python and supports many features: rooms, NPCs, items, player skills and stats, ANSI colors, a help system, damage/healing, etc. SQLite is used to store the data, so no files are required for building (unlike LPMUDs). Short and easy internal commands take care of the development and maintenance.
FIFE is a cross-platform 2.5D game creation framework written in C++ and Python. Games can be created with a combination of engine, editor tools, game specific scripts, and game content (e.g. maps, graphics, and sounds). The framework is not tied to any type of game (e.g. RTS, RPG), but instead provides a flexible platform for all of them. It supports different isometric views and a pure top-down view. Instead of full 3D flexibility, the engine focuses mainly on using high quality 2D graphics. This puts fewer demands on target platforms and also simplifies the framework and game development.