No Gods, No Masters is an achievement/trophy and final main quest in Fallout: New Vegas if you choose to ignore the 3 other main factions (NCR, Caesar's Legion, and Mr. House) and go it alone, by using Yes Man to help you to fight for an independent New Vegas. Ensure that you have gone to the underground bunker and upgraded the Securitron Army prior to talking to Yes Man at the conclusion of Wild Card: Finishing Touches.