Bioshock 'Constants'... let's list them (Spoilers... obviously)
I was thinking about this even before I knew the ending: Bioshock and Infinite share tons of concepts, character-types and plot points. So I thought I'd list the ones that stuck in my mind and ask around for more that I might have missed:
1. Setting. Both games take place in highly "improbable" cities (bottom of the ocean vs. 20,000 ft. up in the air). Both are accessed by the player via a small capsule (bathysphere/rocket), which are both launched from a lighthouse.
Both cities have cut the ties to regular society and regard themselves as a kind of haven for disgruntled elites. Rapture was founded on that very idea (being a haven where the world's brightest heads could thrive with minimal government intervention), while Columbia seceeded from the Union to pursue its own radical ideals.
2. Anachronisms: Both games are set in the past (1912/1960) but feature environments and technology that are so advanced that they'd be highly futuristic even by today's standards.
3. Class struggle: Both cities are dominated by cutthroat capitalists who are challenged by some sort of underground worker-movement who want to take control away from them. In both cases, the leaders of these so-called freedom fighters turn out to be just as evil as the ruling elite they're fighting.
4. Main antagonist: Both games have mysterious main baddies, who get virtually no screen time, but are still always present through voice recordings, posters and rants on the PA-system. Both baddies are killed off rather anticlimactically and in a very, errr, personal manner by the player.
5. Secondary villains: In both games, these are the leaders in the fields of industry/art/etc. in their respective cities.
6. Plasmids/Vigors
7. Player character has a mark his hand/on his wrist (chain tattoo/"AD").
8. Both games have girls with special powers as pivotal characters. In both cases, those girls have some sort of mechanical/mechanized guardians which are incredibly vicious towards enemies, but incredibly gentle towards the girls. Both guardians use green/yellow/red light emanating from their heads to convey their current state of aggressiveness. Heck, Elizabeth even looks like a grown-up version of a little sister IMO.. :)
There's probably tons more, so feel free to add to the list.
S.