TURBU is a game system for creating and playing console-style RPGs, designed to be compatible with RPG Maker 2000 and 2003 games. But unlike other projects that aim to create RPG Maker clones, TURBU is its own system with its own file formats. It doesn't play RPG Maker games directly, but rather converts them to TURBU projects via an importer. This leaves the TURBU engine free to add new functionality that's not supported by RPG Maker, such as improved scripting, directly in the game engine instead of having to use patches and hacks to hook the new features in.
The engine is currently in active development, able to display maps, move around on them and move from one map to another, and run event scripts. The majority of script commands are currently supported, and the rest are being worked on. The editor allows maps to be created and worked on, and actually hosts the game engine inside the editor, which means that it's possible to test a game without having to launch an external program.
There is currently no battle engine. There are two planned, (one for RM 2003-style games and one for RM 2000-style games,) which will be added once development of the map engine is finished.
MPL 1.1 (Open-source. Source code is available at http://code.google.com/p/turbu/)