Take it Back!

Take it Back! is the final quest in Fallout 3 as well as an achievement and trophy.

Synopsis
Following Colonel Autumn's act of rebellion and the general order to rally at the Purifier, Elder Owyn Lyons decides to strike, delivering a crippling blow to the Enclave forces in the Capital Wasteland and securing Project Purity. Liberty Prime will spearhead the attack, followed by Lyons' Pride, Sentinel Sarah Lyons, and the Lone Wanderer.

Walkthrough

 * The quest is divided into two parts. The first is an extended interactive cutscene as Liberty Prime fights its away across the Arlington Bridge, wiping out all Enclave soldiers, emplacements, fortifications, and Vertibirds in the way. Lyons' Pride follows close behind the machine. It's recommended to save right at the beginning of the quest, especially on weaker machines, as performance tends to dip during the fighting.
 * Sentinel Lyons and Knight Captain Gallows are marked as essential characters and cannot die. This does not apply to the four other members of the team, namely Knight Captain Dusk, Paladin Glade, Paladin Kodiak, and Paladin Vargas. Knight Captain Colvin does not appear. Any survivors will appear in Broken Steel, except for Paladin Vargas. If the player kills any of them, Liberty Prime turns hostile... with predictable results.
 * At the end of the Bridge, the Pride hangs back while Sentinel Lyons follows the player all the way to the Purifier.
 * Inside the Purifier, the player has to fight through to the Jefferson Memorial rotunda and the control panel for the Purifier. Inside, Colonel Augustus Autumn confronts the player. To get rid of him, the options are twofold:
 * Kill him and his men.
 * Convince him to leave by:
 * Persuading the Colonel that he's a pawn in Eden's machinations (Charisma 7).
 * Pointing out the Enclave's lack of legitimacy (Intelligence 9).
 * Arguing that his entire fight is meaningless (Speech check of 55 and 70).
 * Once the Colonel is out of the way, the player has to activate the purifier to conclude the quest.
 * Inserting the modified FEV in the interface inside the airlock will fulfill Eden's request, grant -1000 karma, and cause Aqua Pura to be damaging to the player and eventually lethal, as well as causing sick wastelanders to appear in infirmaries across the towns in the Wasteland.
 * As the chamber is filled with radiation, the player has to either enter it themselves or demand Sentinel Lyons to input the code. Refusing to do either will cause the purifier to explode, ending the game regardless of Broken Steel. The code is 2-1-6, corresponding to Revelation 21:6, James' favorite passage from the Bible.
 * Companions will refuse to enter the chamber, even if they are obviously radiation-proof (Fawkes, Charon and RL-3). Their refusal messages are as follows:
 * (Broken Steel)
 * Dogmeat whines in response.
 * (Broken Steel)
 * If Broken Steel are installed and active, all three radiation-proof companions will agree that the smart way to handle the situation is to leverage their resistance, rather than endanger standard-issue humans.
 * Regardless, if the proper code is entered on time, the game will end properly and, with Broken Steel, progress into the add-on.
 * If Broken Steel are installed and active, all three radiation-proof companions will agree that the smart way to handle the situation is to leverage their resistance, rather than endanger standard-issue humans.
 * Regardless, if the proper code is entered on time, the game will end properly and, with Broken Steel, progress into the add-on.
 * If Broken Steel are installed and active, all three radiation-proof companions will agree that the smart way to handle the situation is to leverage their resistance, rather than endanger standard-issue humans.
 * Regardless, if the proper code is entered on time, the game will end properly and, with Broken Steel, progress into the add-on.
 * If Broken Steel are installed and active, all three radiation-proof companions will agree that the smart way to handle the situation is to leverage their resistance, rather than endanger standard-issue humans.
 * Regardless, if the proper code is entered on time, the game will end properly and, with Broken Steel, progress into the add-on.
 * Regardless, if the proper code is entered on time, the game will end properly and, with Broken Steel, progress into the add-on.

Bugs

 * Liberty Prime and Sarah Lyons are subject to all standard gameplay bugs, including misfiring scripts, lost pathing, and other errors. A simple reload usually suffices. If Lyons refuses to follow the player, is a quick fix for PC players.
 * Telling companions to wait at the rotunda before activating the purifier will cause them to be lost, as the Broken Steel interior is a separate cell. The command will teleport the player to them, allowing them to be reacquired.
 * Leaving when the opening cut-scene for the quest plays will result in the quest breaking.