...As for now, the gui System is CEGUI cause it can use the same data types as the Engine's.
Currently Third Party software supported:
Partial* Tiled Map support
Partial* Dark Function Editor Support
*By partial, means that the Engine uses only a part of the features provided by the software (For now).
The Engine provides the "Standard Zeta Lua Library" with useful pre-defined Lua scripts for easier game creation. Also there is a Demo demonstrating some of the features.