I like everything except your text-to-speech program. You really ought to either try and say it yourself, or get someone to volunteer to do it. Text to speech is really poor still to this day.
I tried the speech myself and while my english is pretty good the end result wasn`t verry good. Probebly because no one likes the hear them selves. That`s why for now I used this speech program. My sister in law is a teacher on the university in english and she is going to redo them when see gets back from her sabbatical. This still a few months away though. For now this is a pretty good solution.

edit: the engine looks POWERFULL¬?¬? when we will can get a copy?
In two to three weeks

but using your own voice would fit better in the final game, i think. But using this sollution is not so bad
Currently I am just focussing on the engine. I am working on a gamedesign document but in to implement I would need a large team.

I'm really impressed by your work so far. Do you wrote the whole engine alone?
And what about the artwork, did you make it yourself? Do you have a good friend that makes it for you, or do you know some good graphics-sources on the web ?
Yes all the engine code is written from the ground up except for some libraries of course for imaging, math etc. The artwork is mostly done by myself. I created the terrain myself in L3DT and the models are made in Deled. Textures for the models mostly come from internet or free mods for games like battlefield 2 and Far cry. Most of these textures have been edited and normalmaps etc are painted by myself. The sounds or from free sites or generated by myself (voices). The background music is the only copyrighted thing in the demo.

What level of detail would your engine be aimed for, considering it's for next gen gaming?
The engine is really made for next generation hardware. I personally use my old geforce 6600 is a minimum. With medium settings the engine gets about 30 to 50 fps in 1024x768. The triangle count per frame I currently work with is 150000. This includes renderings for reflections etc. It will probebly run on much lesser hardware because then engine has a sh*tload of settings that can be changed. But to see it in all it`s glory I recommand a gf 7800 or higher. CPU and MEM are a 1.8 ghz pc and 512 or 1024 mb. Depends on OS.