When staring into the combine portal at the end of HL2, seeing the several citadels inside it, I always imagined a world vastly different from our own. Gravity might work differently, producing planets in other shapes than spheres. Xen has physics that makes no sense to us, and the combine technically has to reside in another dimension because otherwise they couldn't travel to ours.

I was actually disappointed over the mention of a dyson sphere in Epistle 3 because it's a concept I can comprehend. There is so much about the combine advisors that reach far beyond our capability of understanding, and in my opinion it should remain that way even after the conclusion in order to preserve their enigma.

In my opinion it should have been referred to as "Something huge and otherworldly, which I could only assume was their universe's equivalent of a dyson sphere. In our universe it would have taken the shape of a sphere, but in this one gravity most likely works differently."

This leaves it open for the reader's own interpretation and preserves the mystery.

Of all the artwork I've seen of this scene, yours is by far the best. It captures a glimpse of a universe where a sphere shaped dyson...shape is not the most efficient one for capturing the star's energy (Star is still round though, but it could be disk-shaped for all we know) You made some thinking outside the box, and came up with something that feels completely alien. Amazing work!