Fallout: New Vegas Scripted Encounters

Within Fallout: New Vegas there are random encounters similar in style to those in Fallout 3. These encounters can happen at specific points or be completely random happening when they happen.

Fallout New Vegas Random Encounters
Several of the Random encounters can be replaced by the Wild Wasteland perk. Most notable of these encounters being the three alien surveyors past the ranch near a hovering alien ship, or the three old ladies in Primm with shotguns.

Powder Ganger Event
Potential to be encountered anywhere, as long as you have bad reputation with the Powder Gangers. A random Powder Ganger will appear and initiate a conversation then attack you.

Star Bottle Cap Encounter
This maybe a triggered event that happens in anywhere after you find a Sunset Sarsaparilla star bottle cap. After obtaining the Bottle Cap, a Roaming Trader will appear and converse with the player about the bottle cap. He has a speech challenge of about twenty five to forty. The trader will talk about the supposed Treasure offered by the Sunset Sarsaparilla Company. If the player chooses to they can kill the Roaming Trader who will have five to seven Blue Star Bottle Caps on him.

NCR Rangers
While traveling the Mojave Wasteland with a negative rep with the NCR, 2-3 NCR Rangers will appear, telling you to change your reputation with them from bad to good within three days, or else they'll attack you "without the pleasant conversation". If you don't listen to him/her, they'll come back and shoot on sight. Most of the time there'll be an Anti-materiel rifle on them and the NCR Ranger combat armor.