inside, the player moves weightlessly through a wire-frame 3D environment, while collecting data and fighting SHODAN's security programs. Actions in Cyberspace sometimes cause events in the game's physical world; for example, certain locked doors may only be opened in Cyberspace. Outside of Cyberspace, the player uses the game's sixteen weapons, of which a maximum of seven may be carried at one time, to combat robots, cyborgs and mutants controlled by SHODAN. Projectile weapons often have selectable ammunition types with varying effects; for example, the "dart pistol" may fire either explosive needles or tranquilizers. Energy weapons and several types of explosives may also be found, with the latter ranging from concussion grenades to land mines. Along with weapons, the player collects items such as dermal patches and first-aid kits. Dermal patches provide the character with beneficial effects—such as regeneration or increased melee attack power—but can cause detrimental side-effects, such as fatigue and distorted color perception. Attachable "hardware" may also be found, including energy shields and head-mounted lanterns. Increasingly advanced versions of this hardware may be obtained as the game progresses. When activated, most hardware drains from a main energy reserve, which necessitates economization. Certain hardware displays the effectiveness of attacks when active, with messages such as "Normal damage". When an enemy is attacked, the damage is calculated by armor absorption, vulnerabilities, critical hits and a degree of randomness. Weapons and munitions deal specific kinds of damage, and certain enemies are immune, or more vulnerable, to particular types. For example, electromagnetic pulse weapons heavily damage robots, but do not affect mutants. Conversely, gas grenades are effective against mutants, but do not damage robots. Plot Set in the year 2072, the protagonist—a nameless hacker—is caught while attempting to access files concerning Citadel Station, a space station owned by the TriOptimum Corporation. The hacker is taken to Citadel Station and brought before Edward Diego, a TriOptimum executive. Diego offers to drop all charges against the hacker in exchange for a confidential hacking of SHODAN, the artificial intelligence that controls the station. Diego secretly plans to steal an experimental mutagenic virus being tested on Citadel Station and to sell it on the black market as a biological weapon. To entice cooperation, Diego promises the hacker a valuable military-grade neural implant. After hacking SHODAN, removing the AI's ethical constraints, and handing control over to Diego, the protagonist undergoes surgery to implant the promised neural interface. Following