No Gods, No Masters

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.

Detailed walkthrough
After telling Yes Man you're ready to go to the dam, you start this quest on the western end of the dam with a Securitron and up to two companions that you might have with you, before you told Yes Man that you were ready to go to the dam.

As you walk forward you will see the large turret to your right explode and you will see in front of you four or five NCR troops ducking behind sand bags while fighting the Legion. You can then sneak past them all, kill them all, or kill just the Legionaries, if the NCR troops are not hostile towards you. There are several legionaries coming from the eastern side of the dam and from the drainage towers to your left as you cross the dam. There are some NCR snipers on top of the dam towers to your right as you cross the dam. After crossing the dam, you will have to enter the last tower to your right, and use the elevator to descend to the Hoover Dam offices.

After entering the offices you will encounter two NCR heavy troopers armed with heavy incinerators burning four Legionaries cowering away from them. You can kill both the legionaries and the NCR troops, sneak past them, or convince the NCR troops with a Speech check of 75 during dialog. Afterwards, install the override chip into the large terminal with several screens attached to it, at the end of the room. Yes Man will contact and inform you that you have two options:
 * Activate the Securitrons underneath the bunker at Fortification Hill.
 * Deactivate the dam's power output, rendering it useless to the NCR.
 * Note: neither of these options will affect the ending you will receive. See Fallout: New Vegas endings for details.

After choosing either option you will have to run through the halls, where more legionaries and NCR troops will be fighting each other. You can either sneak past them all, kill them all, or kill the legionaries if the NCR troops aren't hostile towards you. To get from the control room to the manual override switch, turn and follow the hall to your left after exiting the control room, then turn to your right down the next hall and go to the end of the hall and turn to your right and open the door to a balcony overlooking one of the dam's eastern plants. Turn to your right and flip the switch, then go straight down the hall where you came from and turn through the open doorway to your left, and use the elevator to ascend to a room inside one of the eastern towers. Inside the room is a staircase to your right after you come out of the elevator. The room upstairs from the elevator are some toilets, sinks, and a first aid box hanging on the wall. You can drink from the toilets and sinks and use the medical supplies from the first aid box to heal your wounds, before you continue to cross the dam. Exit through the door to the left of the elevator if the elevator is behind you.

As you cross to the eastern end of the dam you will see fires burning at Fortification Hill, if you decided to activate the Securitron army. Several more legionaries will be coming from the power output towers to your left and from the eastern end of the dam and they may try to take cover behind the sand bags, there are also some NCR snipers on top of the towers, including the tower you came out of. If you completed the quest Volare! and helped the Boomers, they will fly the restored B-29 over the dam and bomb a number of the legion. If you completed the quest For Auld Lang Syne and told the Enclave Remnants to assist the NCR against the Legion, they will fight by your side, if the NCR is not hostile towards you, but if the NCR is hostile towards you then Cannibal Johnson will attack you making it very likely that you have to kill them all, except Daisy Whitman who flies away inside the Enclave vertibird. If you decided to activate the Securitron army, then you will have several Securitrons to assist you in the battle. After crossing to the eastern end of the dam, you will have to cross the bridge to your right and follow the path to the gate leading to the legate's camp. (The path has more legioniares coming from the legate's camp to kill or sneak past.)

Follow the path down the hill from the gate and enter the legate's camp to your right. Inside the legate camp are some praetorian guards and some other legionaries to kill or sneak past. Go up the hill to meet Lanius and either kill him and his legionaries in a duel, or convince him to surrender with numerous Speech checks of 55, 65, 75, 85 and 100. The Barter check will ultimately result in combat. After making either decision, go back to the gate at the camp entrance and you will be confronted by General Oliver, six NCR Veteran Rangers, and the choice to kill them, convince the NCR to leave, or to throw Oliver off the Hoover Dam.

Behind the scenes

 * The phrase's origins date back to the late 19th century France, where it was coined by the socialist Auguste Blanqui. "Ni dieu, ni maître" -- "neither God, nor master." Since then, the phrase has been used by anarchists.


 * If you are listening to the NCR Emergency Radio during the final battle for Hoover Dam, among the chatter about positioning snipers and reinforcing positions you may hear the lines "They're coming out of the walls man! They're coming outta the damn walls!" and "Game over man! GAME OVER!" This is a reference to Bill Paxton's character Private First Class William Hudson from the film Aliens.
 * The voice will also reference Doctor Who, with location Bravo Bravo Charlie (BBC) being mentioned just before saying "The Doctor is coming", and Lost, by telling 4 to reinforce 8, 15 to reinforce 16, and 23 to await reinforcement by 42.

Bugs

 * After you receive the briefing from Yes Man about what needs to be done at Hoover Dam, the game presents a pop-up warning about moving into the endgame. If you do not say that you want to move on to the end of the game, and leave New Vegas, this quest will not load and the gate to enter New Vegas will be locked, preventing you from getting back into the Lucky 38. A fix to get back into The Vegas Strip is to pull-up the console with the "~" key, click on the door to select it and type "unlock". This unlocks the gate and allows you to continue.
 * If you choose to run back out of the gate before facing the Legate, then you can fast travel from the area. Doing so causes you to be unable to fast travel from another location. This can be dealt with by walking into a building and back out, but you must do this every time to continue fast traveling.
 * Game always crashed to desktop when engaging the first legion soldiers. After leaving Boone inside the first building and engaging the legion alone, the game worked properly.
 * After telling Yes Man that you're ready to go to the dam and if you have ED-E with you, ED-E will stay in the same spot where you start at, as no companions are allowed into the Lucky 38 penthouse, so he'll stay in wait mode as he was left as in the floor he was in. To fix this you have to open the companion wheel and tell ED-E to stay, afterwards tell ED-E to follow you.
 * - Xbox/PS3 unconfirmed. "East Power Electrical Switch". Before attempting the mission it is possible to activate this switch so when you're on the actual mission there are no interactions with it available. Simply continue and "Exit out to the east side of the Dam". This step in your quest log will remain uncompleted but will not affect the outcome. When confronting General Oliver the Securitron Army will still appear.
 * If you kill Legate Lanius by a sneak attack critical from afar your quest log will still tell you to deal with him, making the quest not able to be completed. (Killing every legionary in the area and exiting through the gate will make the quest go on as it is supposed to.)

Freiheit zu, Freiheit von Żadnych Bogów, Żadnych Panów Ни богов, ни господ