Silent Running

 is a perk in Fallout, Fallout 2, Fallout 3, Fallout: New Vegas, Fallout Tactics, and J.E. Sawyer's Fallout Role-Playing Game.

Fallout, Fallout 2 and Fallout Tactics
With this Perk, you now have the ability to move quickly and still remain quiet. You can Sneak, and run at the same time. Without this Perk, you would automatically stop Sneaking if you ran.

Fallout 3
With the Silent Running perk, you gain an additional 10 points to Sneak, and running no longer factors into a successful sneak attempt. Drastically increases your ability to crouch-run through buildings getting free sneak criticals on everything in sight. Together with the Chinese Stealth Armor, the player is able to sneak as efficiently as possible. For combat, consider using a silent weapon such as the Dart Gun or Perforator to remain undetected. Despite being labeled as "silent" running, you still generate the same amount of noise from your footsteps as usual, but NPCs don't react to it.

J.E. Sawyer's Fallout Role-Playing Game
With this perk, you now have the ability to sneak while running without penalty. Without this perk, sneak chances are halved when running.

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