Casino games/Blackjack

*Blackjack* is a casino game found in many video games as a minigame used to gamble in-game currency. They will typically be identical to real-world examples, most often using S17 dealer rules with the American hole card, but without any of the additional rules and variants listed below.

In blackjack, the house advantage is found in the fact that the player loses if they bust, regardless of whether or not the dealer also busts. The decisions made in each hand can greatly affect the outcome, and as such strategy is an important part of the game.

## Rules

Blackjack is played with cards; however, there is no consensus or standard on how many decks should be used - games with 1, 2, 4, 6, or even 8 decks of cards are played. This has no effect on the rules used in the game.

Each player is dealt two cards; the dealer is dealt one card face up, and typically a second card face down. Suits are usually irrelevant; cards are valued 10 for a face card (Jack, Queen, King), 2-10 for numbered cards, and 1 or 11 for an Ace, depending on whether it being 11 makes the hand bust or not. If the player's total hand value exceeds 21, they have bust and lose their bet.

While a player has not bust, they may choose to take an extra card to try to increase the value of their hand without exceeding 21. If the player has an Ace valued at 11, they cannot bust by drawing an extra card, as the Ace can change to a value of 1 instead.

After the players have either bust or decided not to take any more cards, the dealer then undergoes the same process; however, the dealer cannot choose whether to take an extra card - instead, there is a rule that determines this. The two most common are S17 (if the dealer's hand is 16 or less, dealer must hit; otherwise, dealer must stand) and H17 (if the dealer's hand is 16 or less, or 17 with an Ace that counts as 11, dealer must hit; otherwise, dealer must stand).

If the player busts, they lose regardless of what happens with the dealer's hand. If the dealer busts, the player wins. If the player's hand has a higher value than the dealer's, the player wins. If the player's hand matches the dealer's hand, it is considered a push and the player is given their stake back. If the player's hand has a lower value than the dealer's, the player loses. All bets are evens, doubling the staked money.

## Additional rules and variants

Except where stated otherwise, these variants are typical when the game is played in a casino, but less common when found in video games.

* **Blackjack**: A hand consisting of only an Ace and a card with a value of 10 is called a blackjack and beats other hands with a value of 21. If the player has blackjack and the dealer doesn't, the player wins. If the dealer has blackjack and the player doesn't, the player loses. This is less commonly applied in video game versions.
	+ If a player wins this way, they are typically paid at 3:2 (x2.5) instead of the usual, but sometimes this is reduced to 6:5 (x2.2) or even no bonus at all.
	+ Sometimes a hand is only considered blackjack if the non-Ace card is a picture card, excluding an A-10 pair.
	+ In games with a hole card, after all cards are dealt, the dealer checks their hole card (without showing playings) and immediately collects all bets if they have a blackjack, unless the player also has a blackjack, in which case the player is given their stake back. If the dealer does not have a blackjack, players with blackjacks are paid for their win before any action from any other players is taken.
		- **Insurance**: If the card shown by the dealer is an ace, the player is given the option of insuring themselves against a blackjack. This is a side bet of up to half the original stake that ignores the player's current hand and simply pays x3 if the dealer has a blackjack.
* **Double down**: The player may double their stake after receiving their initial cards, on the condition that they draw exactly one more card, leaving their hand with three cards.
	+ Sometimes the player can double down at any point in the hand.
	+ Sometimes the player is limited to only doubling their stake, and sometimes it can be any additional amount up to their original stake.
	+ Sometimes the player is only allowed to double down if their hand is of certain values.
* **Split**: When the player is dealt two cards of the same value, they can be split into two separate hands; the player repeats their stake and is treated as though they had bet on two hands; each of their two initial cards becomes the first card in each of the two hands, and a second card is dealt to each hand. The player wins or loses the two hands separately.
	+ Sometimes hands cannot be split unless the two cards are also of the same rank, so only hands that consist of pairs can be split, excluding hands such as K-Q or Q-10.
	+ Usually, a pair of Aces cannot be split, but in some rulesets they can. It typically comes with the restriction that the player must stand after both hands have been dealt their second card.
	+ The blackjack rule does not usually apply to split hands, but this isn't always the case.
	+ Sometimes these hands cannot be doubled down on or split, and sometimes there is a limit to how many times a hand can be split in one game.
	+ Sometimes the player is limited to matching their initial stake, and sometimes it can be any additional amount up to their original stake.
* **Surrender**: Before receiving any additional cards, a player may choose to surrender their hand, returning 0.5x their stake.
	+ This is usually done after blackjack checks and insurance bets, if they are in play, but sometimes it can be done before.
* **Five card charlie**: This is almost never found in casinos, but is more common in video game implementations. A player who has a hand of five cards and has not bust automatically wins.
* **No push**: This is almost never found in casinos, but is more common in video game implementations. If the player and dealer have the same value hand, instead of being given their stake back, the player loses.
* **Jackpot**: This is almost never found in casinos, but is more common in video game implementations. Having a hand of 7-7-7, or 6-7-8, or J-Q-K (normally bust, and requiring the player to hit on a hard 20) awards the player with a large bonus.