Seeing a lot of mistakes in it though, maybe not the best place for the unfamilliar to start as they'll be mislead. The Flood came after the Forerunners hunted down the Precursors, from the powder some of the remaining Precursors turned into to preserve themselves until a safer time. Some think the powder waited too long and mutated into the flood, some think the Precursors intentionally mutated into the Flood.



The prophet-Elite aliance never used Precursor artifacts, those were based on Neural Physics and so were completely destroyed when the Halo rings fired.



etc etc, a few smaller things.