|First Found on||Level 2 - Research|
Isotope X-22 is a key item found in System Shock.
It can be found in the southernmost quadrant of Level 2, in the westernmost room past a bulkhead that requires a Science Access Card to open. There it will be inside a room clearly marked with radiation danger signs, under a shield that can be disabled with a nearby button.
Dr. Nathan D'Arcy attempted to use Isotope X-22 in a desperate bid to stop SHODAN from firing Citadel Station's mining laser against targets on Earth, but was assassinated by one of her cyborgs before he could do so. Furthermore SHODAN placed the isotope in a radioactive room and recalled the station's hazard suits to prevent attempts to retrieve it.
In order to overload the laser with the isotope it must first be placed in the Radiation Shield Generator on Level R, and the Laser Override Code entered in a keypad on that same level. This can also be done in reverse. Finally the laser itself must be fired from the large red control button in the central room in Level 2.