In a different post at HBO, Ape Man mentioned that there seem to be some items that indicate a deeper Halo-Marathon connection than just the logo on the side of the Pillar of Autumn as seen in the intro video. The suits that the SPARTAN cyborgs wear are called Mjolnir suits, just as the cyborgs in Marathon were called Mjolnir Mark IV cyborgs. There's also a mention of a lost Mars massacre. As for the chronology, it looks like a wave of colonization could have occurred between the Marathon's launch and when it arrived at Tau Ceti-- but there are still lots of unanswered questions-- such as if FTL flight was developed after the Marathon's launch, why didn't they send a ship to intercept her and bring the crew to Tau Ceti faster?