Thanks for the link. It definitly is a really interesting engine.
There is in fact a simple FPS style sample game, included in the SDK available on the site.
And there is a commercial game developed with the GIANTS engine.
http://www.landwirtschafts-simulator.de which is going to be shipped wihtin the next 2 weeks.
The engine is scriptable using the lua language, which is extremly powerful, fast and easy to code.
Im sure I will have lots of fun with this great piece of software.