In
Bioshock, a
Rosie is one of two types of the
Big Daddy types of enemies. For those unfamiliar with the game, Bioshock takes place in 1960 in a giant underwater city called
Rapture that was built in the post
WWII years.
A Big Daddy is one of the many
genetically modified beings you will find in the city; they tend to ignore the player unless you either attack them first, or attack the
Little Sister they are guarding. The Little Sisters gather genetic material,
ADAM, to fuel the
underwater war machine in the city.
The Rosie's choice of weaponry? A
rivet gun.