Finding the Garden of Eden

 is a Fallout 3 quest. It is also a Xbox 360/PC achievement and a PlayStation 3 Trophy.

Retrieve a G.E.C.K. from Vault 87.

Enter Vault 87
Depending on your choice during Picking Up The Trail, you either have to fight your way through Murder Pass to the vault door and enter or you find yourself directly inside the vault.

Find a G.E.C.K.
Both entrances of Vault 87 lead to the Reactor Chamber. From there, you proceed to the Living Quarters, then the Test Labs. There, you eventually encounter a literate Super Mutant named Fawkes who asks to hold a conversation with you over the intercom. Fawkes explains his upbringing in the vault and how he has become literate and civilized through continued access to the vault's database. Fawkes promises to retrieve the Garden of Eden Creation Kit from the irradiated halls above if he is released.

The radiation level where the G.E.C.K. is stored is extremely high. You can proceed in one of two ways:
 * Attempt to get the G.E.C.K. without help. If you choose to do so, sufficient protection will be needed to resist the radiation and/or some RadAway. A piece of armor to protect against the radiation is in a locked storage room near the G.E.C.K.
 * Release Fawkes, who will assist you in both combat and obtaining the GECK, thus fulfilling the objective of the quest. See Free Fawkes below.

The room with the G.E.C.K. can be found by going left from Fawkes' cell. If you release him, he leads you to it and will engage the remaining enemies in melee.

(Optional) Free Fawkes
Fawkes can be released in two different ways: either starts with going down the hall on the right, and into a maintenance room with 2 Super Mutants. There is a Fire Control Console here that can be activated to unlock all the cells, or a Hard terminal next to it that can be hacked to open his cell directly.

Attempting to unlock the door through the terminal next to his door or by picking the door itself will result in a message saying the door is jammed.

The rooms contain...
 * Room 01 - 3 dead people (2 Wastelanders and 1 Raider)
 * Room 02 - vacant (Centaur possible)
 * Room 03 - The only "dangerous" test subject, a nutty human named Sid in room 3. If you unlock the door through lockpicking, he may be spoken with, where he will babble insanely, including how everyone is dead and "it's all [his] fault", and to "get out of his head". If the door is unlocked through the terminal (be it his or the master one) or the Fire Control, he will turn hostile.
 * Room 04 - vacant (Centaur possible)
 * Room 05 - Fawkes

Once Fawkes is free, he will thank you, and hold up his end of the bargain. He will proceed to slowly walk to the room with the G.E.C.K., fighting any enemy Super Mutants along the way. Once he's there, talk to him again to get him to go retrieve the G.E.C.K. - he can be watched through the windows as he does this, or alternatively followed (talking to him during this will give an amusing comment).

However, if Fawkes is killed, the player will have no choice but to retrieve the G.E.C.K. on their own. Fortunately, the Super Mutant is very tough, and the only way it will happen is if the player does it. A notable way of doing so is to use the "Terminate Specimen" option on the Hard Terminal next to his cell. Doing this will result in Bad Karma. You can do the same to any of the other specimens, although without the Karma loss. If Fawkes is engaged and killed after he has picked up the G.E.C.K. but before giving it to the player, it can be retrieved from his corpse.

Escape from Vault 87
Unfortunately, even after all this effort you will be incapacitated upon attempting to leave the vault by a type of flashbang bomb, and Colonel Autumn will show up with some Enclave soldiers, and take the G.E.C.K. from you. An exception to this is in the Bugs section below...

Followers
If you are accompanied by a follower NPC, they will not be with you after you have been incapacitated by the Enclave. Be sure to retrieve any equipment from them you do not want them to walk off with (as if they were fired) before this happens, or right after retrieving the G.E.C.K. You will not have a chance to re-hire your companion until after The American Dream.

It is not necessary to release your companions before the scripted event, however. They are not killed by the Enclave, instead they return to their default locations soon after you escape the Enclave. For example, Dogmeat will be waiting by the Vault 101 entrance. They also still have all the equipment you have given them. You have to do any necessary Karma checks again though and Fawkes may be a more desirable companion anyway if you have chosen to free him.

Bugs

 * Fawkes may get stuck between a wall and a machine for a while when walking to the G.E.C.K. If that happens, the player can give him a shove to help get him out.
 * On some occasions, Fawkes will seemingly fail to retrieve the G.E.C.K., but it actually gets transfered into his inventory instantly. This seems to happen when he tries to walk up against something and finds his path blocked.
 * Using the above bug in addition to the door locking quirk allows the player to escape Vault 87 with the G.E.C.K. in hand. When Fawkes gets into position to get ready to be ordered to take the G.E.C.K., the player must attack him and turn him hostile. Fawkes should then be guided through the Vault until the ambush point is reached (maybe a little beyond to be on the safe side), and Fawkes must then be turned friendly again. The easiest way is through ducking and using a Stealth Boy. Once that is done, talk to Fawkes and he'll go retrieve the G.E.C.K., but find his path blocked by the locked door. The bug will kick in, and Fawkes will have the G.E.C.K. At this point, he will try to find a way to the point where he stands after getting the G.E.C.K., allowing the player to talk to him and recieve the G.E.C.K. while out-of-range of the trigger point for the ambush. Unfortunately, the game will not acknowledge this as completion of the mission.
 * Note that if any followers are present, they must be left a safe distance away, or they will engage Fawkes. Even if he is turned friendly again, they will continue to attack.
 * Occasionally, even followers you've left standing around somewhere will get respawned to their default positions after the Enclave captures you. You may even be able to hear Dogmeat's panting during the cutscene.