Silent Running

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

Fallout, Fallout 2 and Fallout Tactics
With this perk, you can use your Sneak skill and run at the same time.

Fallout 3
With this perk, you gain +10 Sneak, and running no longer factors into a successful sneak attempt.

This perk drastically increases your ability to crouch-run through buildings, getting free Sneak Attack Criticals on everything in sight. Together with the Chinese stealth armor, the player is virtually invisible to non-player characters even when using the Pip-Boy 3000's light. For combat, consider using a silent weapon such as a melee weapon, or a gun with a silencer such as the Perforator or silenced 10mm pistol to remain undetected.

Fallout: New Vegas

 * With this perk, your running no longer factors into a successful sneak attempt.
 * If you are a melee or unarmed fighter and rely on sneak attack criticals then this perk goes very well with Travel Light, Implant M-5 and Tunnel Runner allowing you to close the distance quickly while remaining silent so you can achieve a Sneak attack critical.

Fallout 4
The effects of this perk are found in the rank 4 of the Sneak perk.

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.

Behind the scenes
"Silent running" is a mode of operation for submarines: all unnecessary systems are shut down, propeller speed is reduced and even the crew is ordered to remain as quiet as possible, all in order to reduce the chances of being detected by passive sonar.

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