Peg your way to 121 points
Cribbage is a two-player race to 121 points. Each hand you and the AI are dealt 6 cards, and each of you sends 2 of them face down to the crib, a bonus hand that belongs to the dealer. The deal alternates every hand, starting with you. A starter card is then cut from the deck; if it is a jack, the dealer immediately pegs 2 points. Click two cards, then press Send to crib.
Next comes the play, led by the non-dealer. You and the AI take turns laying cards face up while keeping a running count, which may never pass 31. Aces count 1, number cards their face value and face cards 10. You score 2 for bringing the count to exactly 15 or 31, 2, 6 or 12 for pairs, three or four of a kind played in a row, and 1 per card for a run of three or more consecutive ranks among the latest cards, in any order. A player who cannot play without going over 31 says go, and the last player to lay a card pegs 1 when nobody can continue. After the play comes the show: the non-dealer's hand, then the dealer's hand, then the crib, each counted with the starter. Fifteens score 2 each, pairs 2 each, runs 1 per card (double runs count twice), a four-card flush in the hand 4 or 5 with the starter (the crib needs all five), and 1 for holding the jack of the starter's suit. The count for each hand is listed on the table before you press Next Hand. Scoring is automatic, and the game ends the moment either player reaches 121.
This is two-player, six-card Cribbage played to 121. You deal the first hand and the deal alternates after that, so the crib switches between you and the AI every hand. All the counting is done for you: his heels on the cut, fifteens, pairs, runs and 31s during the play, the go, and then the show, where the non-dealer's hand, the dealer's hand and the crib are counted in that order. Each count is listed on the table with its fifteens, pairs, runs, flush and nobs before you deal the next hand. The Count box keeps the running total of the play in view, the game simply refuses a card that would take the count past 31, and the game ends the moment either side reaches 121, even in the middle of a hand.
The AI decides from its own cards, its own crib discards, the starter and the cards already played; it never sees your hand or your discards. How it builds its hand depends on the level. Medium keeps the four cards that score best on their own, counting what its two discards are worth to the crib as a plus on its own deal and a minus on yours. Hard goes further and averages every possible starter card, so it keeps hands with good chances on the cut and avoids handing you fives, pairs and fifteens on your deal.
Easy throws two random cards to the crib and plays a random card from those that fit under 31. Medium keeps the best-scoring four cards and, during the play, takes whichever card scores the most points right away, otherwise laying its lowest card. Hard chooses its discards by averaging its hand and crib value over every possible starter, and in the play it weighs each card's points against what you are likely to score in reply: it avoids leaving the count on 5 or 21, avoids setting up pairs and runs for you, and holds its low cards back for the end of a sequence. AI Training scores its kept cards over every starter as Hard does, but values the crib by also sampling the two cards its opponent might throw in, and during the play it simulates the rest of the pegging against hundreds of hands you could be holding and lays the card with the best average points difference. Over 960 test games against Hard it won 512; the deal still decides plenty of games.
For the complete rules, the deeper strategy and the history of the game, read the full Cribbage guide, or browse guides for all 33 games.