BioShock

Gatherers (Little sisters): Originally to be portrayed as slug-like, genetically modified sea creatures but now shown as genetically modified children, the Gatherers were created by a scientist named Dr. Tanenbaum as a solution to the ADAM shortage. They extract ADAM from the dead with the tools they carry and eat it, their bodies reprocessing it into a usable form, known as EVE. The team designed them so the player would have a moral conflict in killing children to obtain ADAM as well as severe difficulty due to their relation to the Protectors as their charges. According to lead designer Paul Hellquist, the Gatherers have a direct link with the main character. In a recently released audio file, Levine described how the player cannot do anything cruel to Little Sisters, only harvest them (which kills them). One cannot shoot the Little Sisters or set them on fire. Rewards for not killing Little Sisters are given by Dr. Tanenbaum, although the rewards are as of yet unrevealed by Levine.



To adapt and advance their character, the player can spend ADAM to gain upgrades called "Plasmids" to modify themselves and give themselves new and/or enhanced abilities and weapons. These are grouped under trees that are Weaponry, Engineering, Active, and Physical. The "Active" Plasmids are essentially alternate weapons, activated by the player in order to be used. The other classes of Plasmids (referred to as "Tonics" in one magazine) are passive, ability-boosters. One mentioned (but unnamed) Tonic causes the character to become invisible when they aren't moving.

The main resources in the game are ADAM, EVE, and money. ADAM is used for character growth, EVE allows the use of Active Plasmids (similar to "mana" in fantasy RPGs) and money allows the purchase of plasmids and weapon upgrades.