Dead Money is set in the Sierra Madre, an opulent and extravagant resort that would have been the greatest casino in the west, had it ever been opened. The bombs fell before the grand opening gala event, and the Sierra Madre froze in time, its state of the art security system locking the place up tight. Nothing could get in, and none of the guests could escape. The security holograms then activated and the once glorious event turned into a slaughter. After many years, the climate control and air conditioning systems within the facility began to spit strange toxins into the surrounding city, causing a red cloud to form over the area - which proved lethal to anyone who tried to explore the city. Only a mysterious group called the ghost people survived to call the city home, trapped inside what appears to be hazmat suits, they wander the streets never speaking to their victims, only capturing them alive and dragging them away to the depths of the city deep within the Cloud.
And so the Sierra Madre faded from memory, only occasionally being seen in posters across the wastes, until it took on mythic ghost story status, a supposed "City of Gold" in the wasteland where all the treasures of the Old World were rumored to be held. It was kept alive as a late-night saloon story by prospectors who'd claimed to have found maps leading there and were willing to part with the map for a few caps... or a drink... or a warm place to sleep.
The Sierra Madre is a place in the wastes, with travelers risking their lives to find it. Only one man truly "found" it and lived. After the fall of HELIOS One, Father Elijah, formerly an elder of the Mojave Brotherhood of Steel, set out to find new weapons to eradicate the NCR, and in the process, he discovered the Sierra Madre. In doing so, he lured others, including the Courier, to the resort, forcing them to navigate the hazards of the Madre and play the pawns in his game to crack open the casino's vault, long since lost to time. If the Courier wished to escape this hellish place, they would have to be clever, and use their new allies as Father Elijah did. The real question is, what really mattered to them? The treasure? Revenge? Survival? Or their humanity?
Installing Dead Money raises the level cap by 5, as with all story add-ons.
It is recommended that first-time players reach level 20 or higher before beginning this add-on.
Despite the warning you receive at the first door in the bunker, you can stay in the Mojave even if you choose to proceed; the actual point of no return is at the end of the bunker with the radio.
Because of the explosive collar with which you are fitted, you will be unable to leave the Sierra Madre until you have completed the story. In addition, it will become important to avoid or disable radios and speakers found around the Villa to avoid a premature and fatal detonation.
Companions cannot follow you to the Villa; they will be dismissed when you reach the end of the hall.
You can explore the Sierra Madre as much as you like after completing the story, but will not be able to return after leaving. You can return using console commands; if you noclip with tcl through the radio at the abandoned Brotherhood of Steel bunker, you will find a "Door to Villa." Using that door will take you back to the Villa, with all the ghost people still alive, holograms working, etc. You even get to keep your items. You can also use player.moveto ref id to teleport any living companions, though they won't be approachable as they disappear after a certain point in the story.
If a player turns in an item of apparel that raises Agility while wearing it, the Agility increase will remain. This can be repeated until the Courier's Agility reaches 10. While this increased Agility improves skills affected by Agility and increases AP, it does not allow the courier to take perks otherwise unavailable, unlike an increase from an implant.
The add-on focuses more on skills than combat, often placing you into Speech, Explosives, Science, and Barter checks that have a large bearing on how companions will treat you. It also focuses on scavenging as well, mainly due to the lack of shops that sell ammo and materials for weapon repair kits.
If playing in Hardcore mode, the sleep meter does not advance, unless the Courier sleeps. There may be a considerable delay before this happens, however.
Since you do not keep your items when entering the Sierra Madre, low-Endurance characters will have a tough time, because healing items are limited to snack foods and the odd stimpak. Do note, however, that you will keep all Quest Items including items such as the Rebreather.
A recipe for stimpaks can be found on one of your first quests, inside the Clinic. This can make it much easier to survive when dropped here without sufficient gear.
Players may also want to note that if they steal the Van Graff combat armor from the weapon container outside of the Silver Rush, the armor will remain in their inventory when waking up inside of The Villa so long as the Birds of a Feather quest is active. This is very useful for low Endurance characters.
If you don't wish to go through the trouble of glitching to get gear, you may also use the Courier's Stash DLC. Start the DLC normally and when the cutscene is over and you have spawned in, pause the game and download Courier's Stash. After it is done downloading you should receive the items, this will significantly help you in the quests that follow in the Sierra Madre.
The add-on as a whole is a reference to the 1948 film The Treasure of the Sierra Madre, in which two people who are down on their luck meet a prospector, and strike it rich after finding gold in the remote mountains. The main conflict of the film is mistrust, a theme which is constant throughout Dead Money.
"Dead Money" is a slang term used in poker to refer to numerous things. Most commonly, it refers to money that is already in the pot and goes only to the winner of the hand. For example, if two players each bet $5 on the first betting round, in the second betting round, there will be $10 in the pot in "dead money." Additionally, it also refers to money bet out but is now facing a reraise. If one player bets $5, and another player raises to $15, the original player cannot retrieve his original $5 without winning the pot - the money is now dead. The term can also refer to a player who believes they have a chance at winning, but in reality, they have almost no such chance due to a lack of skill or experience: "Bob wants in. Let him join, he's dead money." Therefore a tournament with many unskilled players can be said to have a lot of "dead money." It is also a reference to how Father Elijah treats the player character and the other NPCs, existing only to get him the technological riches of the Sierra Madre - to him, they are all "dead money."