I was just playing ODST and started realizing how many parallels there are with Marathon.
-the player character emerges from a malfunctioning pod and must contact the local service AI in order to find out what is going on. They are then guided by said service AI for most of the game until it is taken offline by alien engineers who turn out to be friendly
-an enslaved hovering pseudo-hive mind engineer species trying to break free
-heading underground in order to find an AI data core that might hold the key to stopping the alien armada en-route to the planet
-a human AI merging with an alien AI and helping the player out
-a service AI going down at a bad time and needing to be reactivated (Sadie's story)
-a service AI with an attitude whose main job is opening doors and stuff.
-said AI’s creator was involved with weird secret stuff and gave the AI secret instructions that lead it to behave unusually
-said creator is already dead by the time we find him
-large weapons caches in places you wouldn’t expect to find them
-the invading aliens destroy a major piece of piece of space infrastructure with a large, radiation emitting, blast (this may be a bit of a stretch but nuking the Tau-Ceti spaceport and bringing down the space elevator with the slip space implosion feel similar)
-the initial alien invasion essentially being a scouting force that is fought off and then a second fleet showing up to finish the job
-more of a Halo 3 thing but an advanced alien species showing up to save our bacon
-on the subject of halo 3, defending an underground human base from an alien invasion.
I know some of these are stretches or just general level concepts, but I feel at least somewhat justified in doing this because of the extreme similarities between ODST and Pathways into darkness. Also this is Marathon and ODST, the connection drawing madness is in full swing here.
