For all its lore, dialogue, and environmental storytelling, there's a lot we still don't know about any other Fallout game, New Vegas is wordy. It has several well-developed, unique factions, some of the series' finest story DLC, and one of the most variable, fleshed-out stories in video game history. But part of its appeal is just how much it leaves to the imagination.

Tie-in media, like the blind spots when it comes to Fallout lore in general, and that's not even to mention all of New Vegas' cut content. Here are ten of the biggest unsolved mysteries in Fallout: New Vegas.

10 What Happened To The Vault 11 Survivor?

A Cut Content Mystery

Vault 11 is one of the darker Vault-Tec social experiments you'll come across in New Vegas. The inhabitants of this vault were instructed to sacrifice one person among their number each year - if they failed to make a sacrifice, the entire population of the vault would be killed by unknown means. The vault dwellers constructed a political philosophy around this idea, eventually forming distinct factions, which, in time, sparked a bloody civil war culminating in a terrible realization.

But it is known that at least one person survived Vault 11. There's even a model for him hidden in the game's files, but he never shows up on-screen. What happened to him after the experiments, and whether he was able to build a new life for himself outside the vault, remains totally open to player interpretation.

9 What Was The Point Of The Hexcrete Archipelago?

What Did The Big MT Scientists Want?

During the New Vegas DLC Old World Blues, you'll encounter a group of mad scientists in the ruins of a once-great research facility, whose grounds are littered with all manner of abandoned and botched experiments. Most of these are explored as part of the story, at least to some extent, but the X-66 Hexcrete archipelago remains a near-total mystery. The area consists of two scattered rows of hexagonal concrete structures of varying sizes. This was, apparently, an attempt by the Big MT research team to experiment with a new construction material called hexcrete.

But what the researchers were actually trying to build here remains to be seen. The buildings aren't arranged according to any sort of pattern, nor can you actually enter them. Were they just playing around with the new material because they could, or did they actually have a purpose or design for these structures? This is never explained.

8 Why Did House Want Vault 21?

What Was Inside?

Robert House is one of New Vegas' most compelling mysteries, though his entire backstory is more or less explored by the end of the game. House is a relentless capitalist, and, if you follow his questline, he's well-equipped to turn you into the same. However, one aspect of his business plan isn't totally explained: his designs on Vault 21. Unlike other vaults you'll explore in New Vegas, though, this one's not a rundown ruin - it's actually an active novelty hotel and casino on The Strip.

It's not unlike House to want to bring the whole of New Vegas under his thumb, but he has a bigger, better casino of his own - what does he want with Vault 21? It's debatable, but his desire to seize control of it may have more to do with the extensive network of tunnels beneath it. It's not clear whether he just wants access to the hidden bunker for strategic purposes, or whether there may be some lost Vault-Tec technology inside he wants to get his hands on.

7 What Goes On In The Legion's Eastern Territory?

Life Back In Flagstaff

The Legion we come to know in Fallout: New Vegas is a ruthless conqueror, characterized by wanton violence, rampant discrimination, and slavery. It believes in its own lofty ideals - a restoration of the Roman Empire in the post-nuclear southwest - but we only see the Legion as it exists on the war front. It's implied that the faction has an expansive reach back east, and the official New Vegas game guide reveals that its empire is centered on the city of Flagstaff, Arizona.

But what daily life is like in Flagstaff remains totally unexplored. Has Caesar achieved a true recreation of Rome as it once was, with its representative democracy and its cosmopolitan diversity? Or is it just more violence and discrimination back home? There's no way of knowing, but we do know that Caesar's Legion is expanding westward for a reason: to grow its population and expand its army so it can continue to grow its borders.

6 What's The Deal With Mr. New Vegas?

On Air For Centuries

One of the most familiar voices in Fallout is that of Mr. New Vegas, the personable host of Radio New Vegas. What many players don't realize, though, is that Mr. New Vegas isn't real - he's an artificial intelligence created before the Great War, in order to entertain the listening public. There's next to no lore about him in-game, although Bethesda developer called him an invention of Mr. House before release.

Mr. New Vegas is voiced by singer and actor Wayne Newton, commonly known as Mr. Las Vegas due to his long-running association with the city.

But that seems a bit of a frivolous pursuit for House, whose main focus is domination. Mr. New Vegas isn't exactly spouting pro-House propaganda; he introduces the next song, he makes a quip, and he moves on. So is House betraying a bit of a softer side, a weakness for music here? Or perhaps this was changed before the game was fully launched. And if he was created before the war, why is he called Mr. New Vegas?

5 How Do You Play Caravan, Really?

No One Really Knows

New Vegas has a couple of mini-games, most of which are centered around its many casinos. There's one mini-game you can play almost anywhere, though: the unique card game Caravan, which is totally unique to New Vegas. It's a deckbuilding game in which each card has a set value, and your goal is to outbid your opponent by having a higher number of cards without falling under the lower limit of 21, or exceeding the upper limit of 26.

But the rules of playing different cards are so complex, and the in-game explanation so unclear, that most players elect to skip Caravan altogether. For those who have consistently refused to engage with the rules, Caravan remains a total mystery.

4 What Does Joshua Graham Say To Salt-Upon-Wounds?

"Kale Watcha Nei Conserva Oh"

If you side with Joshua Graham during the Honest Hearts DLC, your final quest will have you following Graham as he sets out to eradicate the White Legs from Zion Canyon. At length, he'll confront its leader, Salt-Upon-Wounds, to whom he'll speak a phrase in the pidgin language of the White Legs, "Kale watcha nei conserva oh!" This phrase has no official translation, and New Vegas' devs have declined to comment, preferring to leave it open to player interpretation.

A common fan theory holds that the phrase translates to something like, "As God is my witness, you will not be spared," or "God may be watching, but He will not save you." It seems likely enough - White Legs pidgin uses quite a few loanwords, so it's safe to guess that "watcha" translates directly to "watch," while "conserva" comes from "conserve." "Nei" could play a role similar to "ne" in French, i.e. as a negation. Whatever he's saying, though, it's abundantly clear Joshua is making a threat.

3 How Much Cut Content Have We Missed?

There's More To New Vegas

Fallout: New Vegas had a notoriously troubled development cycle, and lots of content was cut from the final version of the game due to development time constraints. So ultimately, no matter how much we explore, there's a lot we'll never quite know about New Vegas simply because it's no longer in the game.

Evidence of much of this cut content still exists in the game's files, and has been found via datamining. We'll never know exactly what was intended for characters like Betsy the Brahmin, Wrench, or Mayor Steyn. Nor will we be able to explore the several cut locations, like Pahrump or Vault 24.

2 Who Is The Mysterious Stranger?

A Bigger Fallout Mystery

A special perk in Fallout: New Vegas (among other Fallout) games allows you to randomly summon the series' most secretive character: the Mysterious Stranger. He'll pop up at random in VATS, finishing off your enemies with a well-placed shot. Although he appears in several entries, and his existence is more directly addressed in Fallout 4, New Vegas still drops the most compelling bit of information about the Mysterious Stranger: the implication that he may have a son.

An NPC named the Lonesome Drifter, who dresses quite a bit like the Mysterious Stranger, may mention offhand that his father was shrouded in mystery. He also carries the same type of gun - the Mysterious Magnum. If you manage to buy it off him, or wrestle it from his cold, dead hands, you may note that when you draw it, it plays the same guitar sting you hear every single time the Mysterious Stranger appears.

1 Which Ending Is Really Canon?

New Vegas Can Go Many Ways

Fallout: New Vegas has a very variable ending, which can change depending on which faction you ultimately sided with, and which sidequests you chose to complete. However, the remainder of the Fallout series has refused to touch New Vegas' ending, remaining largely reluctant to declare one option canon, or speak on what may have happened after the events of the game. This is, of course, intentional. You want players to feel they've had an impact on the world of New Vegas, and retconning their decisions in later works can be frustrating, if not alienating.

But still, the world of Fallout goes on after New Vegas - the TV show is set some years later - and somewhere, there must be an answer. Season two may decide to comment on what really happened at the end of the courier's journey through the Mojave, but for now, the true ending will remain Fallout: New Vegas' most enduring secret.