Both of the games story start with vulnerable amnesiacs, summoned for unknown purposes and guided by seemly trustworthy characters.
in Bioshock Atlas
and in System Shock 2 Dr. Janice Polito
.
Taking their orders and adapting into hostile unknown environments. Bioshocks environment taking place in the underwater city of Rapture, System Shock 2’s upon the Von Braun spacecraft.
Both of these environments also used to harness scientific genius and upon some form of scientific discovery, Bioshock’s discovery being ADAM/Plasmids and System Shock 2’s being the eggs of The Many. Both of them seemingly take over the environment and lead everyone and everything into a state of madness.
The trustworthy characters are revealed to be others in disguised voices, both with an intention to control the environment for their own purposes.
Bioshocks being Frank Fontaine
disguised as Atlas
.
System Shock 2’s being SHODAN
disguised as Dr. Janice Polito
.
Both who thematically, turn out to be dead.
The revealed characters in general are also the cause of the madness, SHODAN being the supposed creator of the ships roaming Hybrids and general mother of
The Many.
Who eventually take over the Von Braun. Frank Fontaine, being the supposed creator of Splicer’s and general usher of the ADAM fuelled Plasmid business, which in the long run without going into to much detail, is pretty much responsible for everyone’s general insanity. Actions of civil war are also present in both games.
In the end, both uncovered characters reveal you have been under their control and have become their monsters. In Bioshock, Fontaines (genetic) monster due to the excessive use of his Plasmids or genetic modifications. Also, in System Shock 2, SHODAN's (cybernetic) monster, due to the usage of her Cybernetic Implants.
In the end, you destroy the main opposing characters.
In Bioshock Ryan
and Fontaine
.
In System Shock 2, The Many
and SHODAN
.
For small details, Ryan explains in the beginning of Bioshock that he had created Rapture, free of petty morality. In System Shock 2, SHODAN explains on her reveal that she had created a new form of life, The Many, with no moral constraints. Ryan in Bioshock expresses similar insults, statements and literal intensions as The Many and SHODAN do in System Shock 2. Fontaine also does so, in comparison with SHODAN.