My dreams are always incredibly realistic and detailed. They are always 3D and colored, although sometimes they can have that 'aged film' look or be oversaturated with color. The physics in my dreams are way better than HL2. The was one dream I had where I saw a waterfall in slow and I could see the water break up into little drops and splash when they hit the bottom. It was so detailed and realistic. And the mind can render stuff like that instantaneosly. It would take a computer weeks to render something that detailed.
And I have had a few dreams where what I dreamt about came true. Like when I was 8, I had a dream and my friend was crying. A few days later my friend burns his finger with a hot glue gun and crys like a little girl . I also remember having a dream about my dog while on vacation. It was a sad dream and I felt bad when when I woke up. Turns out he died while we away.
Its very strange how our minds work and I believe there is much more to the mind than what we percieve.