In Stealth-based video games, a Ghost run (also known as a Stealth run or Ghosting) is a term used to describe a playthrough by the player to go through the game without being detected and without interacting with the guards, if possible, through the entire game.
A Ghost run is a fan term that is popular among the stealth game community to describe the challenge of completing a stealth game without being detected (with forced-detection sections not counted), or without killing (or, if possible, interacting with) enemies in the game. There are different concepts by various type of stealth fans about what ghosting really means, but the general concept means to move through the area without interacting with enemies, if possible, and to leave the environment the way it was. This includes closing doors or windows that the player has opened, not picking up items in the environment, or if possible to avoid having enemies enter into even a 'suspicious' state.
The term 'ghosting' had been used by the community of the popular stealth series 'Thief', of which fans of the games would attempt ghosting playthroughs to complete the game. With the elements of the Thief games incorporated in the Splinter Cell series since the first title, Tom Clancy's Splinter Cell, many fans of the series have attempted these in the community and posted videos online of their walkthroughs, counting things from forced knockouts to the distraction count. Ubisoft Montreal had even implemented a Mission Rating system to track the player's stealth score, but a rating system that fell more in line with rating a Ghost run was not added in until Splinter Cell: Double Agent, which deducted points from the player even if they knocked out an enemy (not counting enemies the player is forced to knock out).
In Tom Clancy's Splinter Cell: Blacklist, 'ghosting' had been added a one of the playstyles for the player to utilize as they play through the game, with the name of the playstyle being "Ghost". With a new point system added in that rewarded the player based on the playstyle used to perform certain actions, the maximum Ghost points rewarded to the player was when they would leave hostiles 'untouched'.