The best source of Adam in BioShock is to collect if from little girls called the Little Sisters, sounds easy right? Well it just so happens that the Little Sisters are protected by monstrous robotic like creatures called Big Daddy. You will be unable to harvest any Adam from a Little Sister unless you've defeated her Big Daddy Bouncer. Once this has been accomplished you are give the option to rescue or harvest the Adam, harvesting results in you receiving more Adam, the option you select will eventually impact the outcome of the story.
When a player dies in BioShock you're not sent back to the beginning of a mission and forced to replay the same battles and storyline encounters over and over again. Instead the game picks up from the point just before your death and continues as if nothing had happened. The same weapons, Plasmids and Tonics remain in your possession and even enemies retain their health, even if they had been injured before you died. This feature does make the game easier regardless which of the three difficulty levels you select but it still has enough challenge to it for most gamers.
Graphics & Audio

Both the graphics and audio of BioShock are excellent and give the game it's life blood. The environments are simply jaw dropping with realistic textures and character models. The artists, modelers, and developers at Irrational Games, who also developed the eerie world in System Shock II, have done a great job using the Unreal 3 Engine, making the underwater city of Rapture come to life with look that is one of a kind.
Finally the voice acting in conversations, audio recordings and radio transmissions are very well acted and believable. This along with the game music and creepy sounds coming from nearly every corner of Rapture fine tune and puts the finishing touches on BioShock.
Bottom Line
BioShock is not without flaws, there have been numerous reports on the 2K Games/BioShock support website with audio, online activation, and installation bugs just to name a few. As mentioned previously the game's three difficulty levels are rather a mute point considering there are no real penalties after your character's death. These issues aside, BioShock is a game that lives up to it's hype and should be at the top of any PC gamers list of must buy games this holiday season.