There is a bit of gameplay at 0:50 and more info from Rand Miller at 4:47.
I love the original Riven. A sequel to Myst, very immersive puzzle games with focus on atmosphere and a deep backstory. The original from 1997 was done with pre-rendered images. The remake will be rendered in real time and will expand the world with new content.
Riven is quite possibly my favorite game ever. I had so much fun just wandering around immersing myself in the world.