I don't know how closely the community is following Destiny here. So much is happening now thanks to seasonal content and yearly major expansions I'm sure it's not the easiest thing to follow lore wise if you're not a regular player? Hell, I play it all the time and the lore still goes over my head, even though Bungie have gotten better and better at integrating it into the actual moment-to-moment gameplay. So I thought I'd provide some updates here, since after direct references to MIDA and K'lia, it's very clear there are strong connections.
-Clovis Bray's Journal
For a collectors addition of a recent expansion, Bungie included what I can only call a 'feelie'. It's a rambling journal filled with diagrams, data logs and rants from the megalomaniacal CEO turned megalomaniacal AI, Clovis Bray. It reads like Durandal's private journal, and that's absolutely intentional. It's the dying Clovis' (all too successful) attempt to become an immortal AI, full of direct and indirect allusions to Marathon, talk of the closure and heat death of the universe, escape, and a project codenamed PFHOR (Competitive Immortality Through Primogeniture of Future-History Ontogeny/Rephylogeny). No I have no idea how that ends up as PFHOR, but it's what they go with.
It's probably not too hard to get your own copy, or a scan. But here's a direct transcript with diagrams: https://docs.google.com/document/d/1tmu9sjYV7c6X1NhRQmOxkj_o7IJ4ZRcifbm49MNr12s/edit
If you have the Beyond Light expansion you can go visit him on Europa. He's a real bore. He does give you a cool sword though.
- The Glycon
One of the most beloved parts of Destiny are exotic missions. Really tough single/coop missions where at the end you get a cool gun. There's usually one every season, but the most recent one really excels. Explore a derelict spaceship just outside the black abyss that once was Mars. It reminds me a lot of that old Marathon fan expansion, Return to Marathon. You don't see a single enemy for about 20 minutes, nothing with you but the creaking of metal and commentary from... interested parties. Every week if you come back to the mission it acts like you're revisiting the ship, and new people will tune in to help unravel the mystery of an attempt to commune with the eldritch beings that just vanished half of the solar system. All in all it gives me the feeling that Bungie would still be able to make an absolutely killer Marathon successor. I'd recommend playing it yourself, I think you only need the free base game and the latest season pass. And the gun you get really is cool.