Liar's Dice is 2+ player dice game that uses an opaque cup or mug and five dice for each player. It takes under ten minutes, but it's quite a noisy ten minutes.
Be the last player remaining with any dice.
Start Each player begins with five dice in an opaque cup or mug. On the first round, a randomly chosen player goes first. Each round after that, the player to the left of the previous starter goes first.
Round Each round, all players roll their dice, keeping them underneath their cups. Players may look at their own dice but must keep them hidden from the other players.
First guess The starting player makes a guess about how many dice there are of one number underneath everyone's cup in total (e.g. "4 twos" or "5 sixes"). Ones are wild, and can be any number.
Next guess The next player on the left must either make a higher guess or call the previous player a liar.
Higher A new guess must be for a higher value of dice (e.g. "3 fours" to "3 fives" or "3 sixes") or a higher number of dice (e.g. "3 fours" to "4 twos," "4 fives," etc.) or both. Play then moves to the next player on the left.
Liar If the player thinks the previous guesser is bluffing or they do not want to bid a higher total they can call the previous guesser a liar. All players reveal their dice. If the previous player guessed wrong (i.e. there are not enough dice to match their guess - they are a liar), they must discard one of their dice. If their guess was correct (i.e. there are dice equal to or more than their guess - they are not a liar), the player calling them a liar must discard one of their dice instead. All players then roll their dice again and a new round begins.
Win When a player has lost all their dice they are out of the game. When all players but one have lost all their dice, the remaining player is the winner.
Ones, being wild, can be both a curse and a blessing. They can allow you to change your guessing quite radically from one guess to the next, but they can also help your opponent to fulfil their guess. If you have a lot of ones you almost always want to be called a liar, because the total for any number will be higher than your opponents expect.
Your ability to bluff goes down the fewer dice you have remaining, but it is still quite possible to catch up after you have lost some dice.
Because the only information a player has about their opponent's dice is the opponent's guess, it's a good tactic to sometimes make a guess that gives false information (hence "liar's dice"). For example, you might guess "4 fours" without having any fours, hoping that your opponent will assume that you have more fours than you actually do. This can backfire if they call you a liar, however.
A large opening guess can be risky, but it forces your opponent to either guess higher (putting themselves at risk) or call you a liar immediately, preventing them from getting any control over the round.