So I’m watching TNG and I come upon the episode “Relics,” episode 4 of Season 6.
Basically the Enterprise comes upon a Dyson Sphere which is 200 million kilometeres in diameter (100 less than the one inside Onyx.) When they come up to it they find a crashed ship from 75 years before that has Scotty in it. After they beam him up they explore Sphere. Eventually the Enterprise finds an entrance. The entrance opens up with blue light and draws in the ship. The inside of the Sphere looks exactly like the one from Halo Wars. The Sphere is abandoned.
So did 343 steal this storyline from this TNG episode (or HW since the world is abandoned.)
The opening to the Sphere looks every similar too. In fact there’s some scenes that look similar to some of the H4 advertisements.
From what I can tell in the H4 concept art video, the UNSC arrives at the Shield World and go inside it. Possibly from the Dawn’s distress signal. This is very similar to the TNG episode where the Enterprise finds Scotty’s signal that’s been going on for years.
Here’s some images of the sphere inside and out from the episode
Also in the episode, it’s stated that the sphere has a internal surface area of 250 million M-class planets (Earth is M-Class.) The Onyx Shield World is 300 million kilometers in diameter. If the TNG guys did their math right, then the Forerunners must have mined out a good section of the galaxy!