Dark Wrote:the only things the techdemo and overture have in common (asside from items) are the main character and the story
And a similar engine (with a few modifications) and a creepy environment, and monsters, and...
I think it's safe to say that they both have quite a lot in common...the biggest differences I can think of are: 1) time spent playing, with the demo being around 1-2 hours, and Overture being about 8 or so, and 2) money, tech demo being free, Overture costing about 20 dollars/Euros.