...seeding a viable option? This section of my lawn receives little direct sunlight. Due to this, moss has grown over many sections and crowded out the thinning grass. I want to re-establish and thicken by over-seeding the grass but do not know whether it is a viable option or just a waste of time given the moss and the lighting conditions.

All the garden experts will tell you that as well as poor light, bad drainage of the soil is a major factor, you can get grasses that will grow in poor light, but not in waterlogged soil. Some suggest that this problem can be solved by spiking the ground with a garden fork about very 4 to 6 inches and a deep as you can, and then raking some course sand over the holes to assist the drainage, you could try this, but if you have a large lawn it's hard work, if you go down this road then use a general purpose fertilizer

There probably isn't enough light for grass, but, maybe they sell a special variety for shady areas. Maybe leave it as moss; you don't have to mow moss!

Fescue should work-- whatever your particular climate is, of course should govern the type of grass you can grow. But fescue grows readily from seeding, fall is best but early spring will work well. Creeping red fescue is best in my opinion, Kentucky 31 is too tall and clumpy and doesn't spread.

Is it out of the question to thin some of the limbs that are giving off the shade? This is an idea. You may even enjoy the newly found light and the different view.