Use an Aerial Faith Plate to launch a turret

Master the Propulsion Gel

Carry science forward

Examine all the vitrified test chamber doors

Obtain 24 medals on the original Arkham City ranked maps (as Batman)

Stand in a defective turret detector

Take GLaDOS' escape advice

Complete the first Hard-Light Surfaces test

Complete the first Thermal Discouragement Beam test

Survive the manual override

Finished the game without using Vita-Chambers.

Completed all research on every subject in Rapture.