Blackjack

Blackjack is a card game in Fallout: New Vegas, playable in any of the six working casinos. Playing 10 hands of Blackjack grants you the Double Down achievement/trophy.

Rules
All casinos in New Vegas use the following rules.
 * Maximum bet is 200 chips.
 * The game is dealt from multiple decks, which are shuffled after every hand.
 * The player may not purchase insurance.
 * Late surrender is not offered.
 * Blackjack payouts and surrendered bets are rounded up.
 * The player can double down on any starting hand.
 * The player may only split to two hands.
 * The player may only split identical card values (that is, the player may not split Queen-King).
 * A card is dealt to the second hand of a split before the player is allowed to act on the first.
 * The player may only double the first of two split hands.
 * The player may draw to the second of two split hands before drawing to the first.

House rules
Each casino has its own rules regarding blackjack payouts and when the dealer must draw. The rules can be seen on the table felts in each casino floor.

Barring variations from Luck, the best odds are found at The Tops, Ultra-Luxe, or Sierra Madre Casino. The worst odds are found at the Atomic Wrangler, thanks to the low blackjack pay out.

Blackjack payout
A blackjack is a hand that is an Ace and a 10 (it is special since it is a 21 with only two cards). If the dealer gets a blackjack, the player instantly loses, without any opportunity to play. If the player gets a blackjack, the player instantly wins and gets a bonus payout based on the casino. A blackjack payout of 3 to 2 means the player gets back 3 chips for 2 chip they wagered.

Given neutral luck (6 or less), a blackjack will occur roughly 5% of the time. A reduced blackjack payout strongly favors the casino.

Dealer must draw to 16, and stand on all 17s
No matter what, if the dealer has a total less than 17, s/he continues to hit. If the dealer has a total of 17 or higher, the dealer stays.

Dealer must hit soft 17
A "soft" hand is a hand that involves an Ace, since an Ace can be either 1 or 11. A soft 17 is any hand where the Ace is used as an 11, since there is still a choice on what the Ace can be. This is contrast to a "hard" 17 that uses an Ace, such as Jack-4-2-Ace. In this case, the Ace has to be a 1 in order to prevent a bust. Under this rule then, the dealer normally stays on 17, unless that 17 was made initially by an Ace being used as 11, at which point the dealer hits again.

On the one hand, this can be seen as increasing the chance of a bust, but because the Ace can be used as a 1 or 11, if the dealer draws a high card, the initial Ace can be used as a 1 instead. Especially since the dealer does not need to play at all if the player busts, the net result of this rule is that the odds increase in favor of the casino. For this reason, Gomorrah and Primm ranks below the Strip casinos in terms of fairness.

Atomic Wrangler (Freeside)

 * Blackjack pays 6 to 5.
 * Dealer must draw to 16, and stand on all 17s.

Gomorrah (The Strip)

 * Blackjack pays 3 to 2.
 * Dealer must hit soft 17.

The Tops (The Strip)

 * Blackjack pays 3 to 2.
 * Dealer must draw to 16, and stand on all 17s.

Ultra-Luxe (The Strip)

 * Blackjack pays 3 to 2.
 * Dealer must draw to 16, and stand on all 17s.

Vikki and Vance Casino (Primm)

 * Blackjack pays 3 to 2.
 * Dealer must hit soft 17.

Sierra Madre Casino (Sierra Madre)

 * Blackjack pays 3 to 2.
 * Dealer must draw to 16, and stand on all 17s.

Playing to Win
As in real life, Blackjack is the closest to being "fair" a casino game can get. That being said, with neutral luck, even with optimal, standard strategy (see wikipedia's entry on strategy which includes a table on when to stay, hit, double-down, and surrender), the odds still favor the house by a margin of a percent or so (though worse at Gomorrah and Primm, even moreso at Atomic Wrangler). Essentially, each game becomes a coin flip.

Starting with a Luck of 7, the odds shift in the player's favor given optimal play. With a Luck of 8, a player can play suboptimally (not surrendering or doubling down on certain hands, for example) and still pull ahead. With a Luck of 10, the player pretty much has to try to intentionally lose in order to not make a scad of caps from Blackjack.

If you try to cheat the system by loading after a loss, the dealer will take a minute to 'change out the deck' before you can continue playing.

Appearances
Blackjack can be played in Fallout: New Vegas.

Bugs

 * The dealer will hit any 17 containing an ace on tables where they must hit soft 17, even if it is not a soft 17 (for example: a king, a six, and an ace).