As we all know, the SoTP team is working to get Halo Rings, (FINALLY) into the game within the next update. What this means is that not only is this a major structure, along with the shield worlds, within the Halo Universe, but it can help out with the develpoment of the game. So here is what I'm thinking we should do in terms of the Flood.
Within the realm of Halo, the Flood have been a horrible parasite that roamed within the galaxy, until the Forerunners wiped them clean. What a lot of people don't know is that there were still flood within the Halo Rings. (And possibly within the Shield Worlds) What I'm saying is that instead of just a single world of Flood that can dominate everyone, what if there is no Flood until some faction within a game explores the Ring. Just like Installation 01, the Covenant searched within the Ring and unleased the flood. Why don't we put this within the game as well.
With gameplay mechanics, I propose that if you have flood turned off, you can still search a ring, (And with a chance of getting the flood) and have it get infested, but not spreading. If the Flood is turned on, once unleashed from the ring, it starts spreading within the galaxy, and the "Pirate" mechanic starts. With the placement of the Rings and Shield Worlds, we wouldn't need to have the flood start off on a regular planet, making the game a lot more lore friendly. That's just what I think should happen for the development of the game.