Frost ODST: Maybe the Shield World in Halo Wars was one of the first attempts at a shield world or a fleet shield world. Either..
A) They attempted a shield world by removing the flood and preventing it from entering... it didn't work so they had to come up with shield worlds like Onyx.
or
B) They needed a way to preserve a fleet from the flood or maintain fleets free of flood infestation so they built a seperate shield world for ships, which is why there is a ship-wide anti-flood beam and a docking station full of ships.
Hah i caught you. You little rascal now I can give you your just deserts.
Welcome to the forums.
You can't play halo wars until you see this video
http://www.escapistmagazine.com/videos/view/zero-punctuation/645-Halo-Wars
I've been perma-banned at bungie.net :(