I think it's nice to notice that hue rotation and making shadows blue is a different technique. In certain games you see a shallow hue ramp, with a sudden jump to a blue or purple on the last colour. This is a great way of suggesting Ambient blue light, which is something you need to create realistic dusk settings. This is why when playing SoM it seems like dusk all the time.
Oh, and atmospheric lighting would fit nicely within the hue rotation topic too. And I think it would be cool not only to discuss the hue ramp, but also the equally important saturation and brightness ramps. Brightness seems like an easy one, because you could just stairstep it through your shades, but imo you get nicer effects with a more parabolic approach.