I want to make games which look as real enough, that it's hard to tell if it's a photo or a in-game screenshot. Yes, I know it's possible to do with Raytracing and make a game like Dragon's Lair which just shows different pictures in Raytracing quality.
Dude, that's one really confused statement. Dragon's Lair was 2D disney-style animation. Plus, there's no such thing as 'raytracing quality' as a standard of image quality.
Creating a game which has photo-realistic imagery is isn't as easy as people imagine it to be. Only the very best renderers (people) can manage something close to real in appearance, even though there are thousands and thousands of other highly trained people out there rendering images with the same tools, trying to achieve the same thing. Plus, 'photo-realistic' is a silly term. People use that term when they're referring to something that looks a lot like real-life, but there are vast differences between human eyes, camera ccd technology and the limitations of monitors. I don't know about you, but my photos usually need a lot of digital darkroom editing before they start to look 'real' to me, and I have a nice camera. Photos are not a good basis for real looking imagery.
The point is, I agree completely with Gabriel. I'd bet more on better artwork and design than trying to reach reality with modern graphics tech. Unless you're a very, very skilled artist, all the tech in the world won't help you.