Minerva's Den is the second singleplayer DLC for BioShock 2, and adds an entirely new campaign, more enemy variants, new tonics, new weapon, and even a new plasmid while keeping the traditional BioShock gameplay. The Campaign was released on August 31, 2010 for Console players and May 31, 2011 for PC players for a total of ten dollars. The campaign adds a new eapon and plasmid, as well as three new locations to the game.
Players take on the role of Subject Sigma, an Alpha Series who regains consciousness in the Rapture Central Computing sector of Rapture while the events of BioShock 2 are taking place elsewhere. He teams up with Brigid Tenenbaum and Charles Milton Porter to combat Reed Wahl and his control on The Thinker, a gigantic supercomputer created by Porter which controls the automated systems of Rapture.
As the story progresses, it is revealed that Subject Sigma is the Alpha Series that Porter became after he was abducted by Andrew Ryan's secret police. The voice of Porter heard over the radio is actually The Thinker's personality duplication program, which ends after the truth is revealed. After The Thinker is dealt with, Porter and Tenenbaum return to the surface in a bathysphere.
Gameplay remains the same from the main game, but adds new tools and enemies to the mix. New Security Bots, a fire-variant Brute Splicer, and a Winter Houdini Splicer type returning from the the first game. The campaign also adds a new Big Daddy variant, known as the Lancer, which sports new armor, new attacks, and a new weapon, the Ion Laser, which the player can use. A new plasmid, Gravity Well, is also added.