Factory Zero

Factory Zero is an achievement/trophy in The Missing Link DLC for Deus Ex: Human Revolution. It is earned by completing the DLC without upgrading augmentations and using weapons.

Overview
Factory Zero, like the Pacifist and Foxiest of the Hounds achievements in Deus Ex: Human Revolution, requires adhering to a specific playstyle from the start of the game until the ending credits.

As the achievement description says, you must fulfill these requirements throughout the whole DLC:

Requirements
 * Do not allocate any Praxis points, no matter how they were acquired: through level up or after collecting a Praxis kit.
 * Do not fire any weapons. Takedowns (lethal and non-lethal) are not considered weapons and can be used freely.
 * Do not throw grenades or place mines.

You can:
 * Throw red explosive barrels and fire extinguishers.
 * Pick up all items safely and sell them. However, it is not necessary to sell anything, because the starting credits (2500) are more than enough to buy all energy boosters and extra health items in the shop. Items that can be picked up include:
 * Praxis kits
 * Rocket launcher parts for the Quinn's Scavenger Hunt side-quest.
 * Quest items: Burke's eye, Data Storage Devices and the Trauma Kit.
 * Use healing and energy restoring items.
 * Equip, aim, upgrade and reload weapons.
 * Equip explosives.
 * Trigger explosive wall mines.
 * (?) Trigger typhoon turrets.
 * Get compromised and set off alarms, although that would make your mission considerably harder. You should try your best to keep a low profile and stay undetected throughout.

All of the Above

It is possible to obtain this achievement by using explosive barrels to destroy the large crate blocking the necessary vent, and then using several of the small boxes laying around to access the raised area in the ducts (2 should be enough). These can be carried (in the proper orientation) though the ducts, and dropped carefully to turn them on end. A well-thrown fire extinguisher can destroy the gas mechanism, but may require several attempts.

Video
600px|left|Factory Zero playthrough for The Missing Link