I just spotted a Halo-Marathon connection, although some people have probably already noticed. In Halo, the Master Chief is aboard the UNSC Pillar of Autumn above the planet Reach as other Spartans attempt to defend the planet. In Marathon, the Security Officer is aboard the UESC Marathon as the other MJOLNIR Battleroid Cyborgs are down on the planet Tau Ceti, defending against the Phfor. Tau Ceti is eventually sacked by the Phfor, killing all of the habitants and the nine Battleroids that were down on the ground, leaving the Security Officer as the last Battleroid. In Bungie's original game manual description for Halo: CE, the Master Chief is left as the last MJOLNIR armoured Spartan alive, as the rest are killed on Reach (we know from expanded lore this is not the case, but still). My point being is that I believe Bungie recreated Tau Ceti as a narrative event in Halo as Reach.