Are you ever at a party, and you think "damn, this party could use some board games"? Me too. Here's some games you can play that require minimal materials.
Materials: Play here.
Players: 4+ (ideally 6+)
A game about inane arguing (also sold as Wavelength). The rules below work for the version above hosted on this site.
Split evenly into teams. On each round, one player chooses a continuum (e.g. Cold to Hot) and receives a secret number from 0 to 99. They must devise a clue that belongs to the corresponding spot on the continuum. The rest of the team guesses the secret value based on the clue. All other teams guess whether the true value is lower or higher than this guess.
The team gets one point for being within 10, two points within 5, three points within 1 and five points if exactly correct. Other teams get 1 point if they correctly guessed lower or higher. Play until a team reaches a fixed number of points (say, 7).
Materials: deck of cards with lots of repeats. An uno deck with the special cards removed works great.
Players: 3-8
A pure bluffing game with a single loser. For an uno deck, the goal is to avoid collecting four cards with the same number.
Play moves around the table. On your turn you draw from a face-down deck and look at the card. You then pass the card to another player, and claim what number is on the card.
The recieving player has two options. They can either predict or pass. To predict, guess whether the player handing you the card was telling the truth. If you're right, they get the card. If you're wrong, you get the card. To pass, look at the card, give it to a different player and make a new claim about the number on the card. The claim can be the same or different to the claim you received. The next player then predicts or passes, and so on.
Materials: none
Players: 2+
Perfect car trip game. Players take turns naming a 'person' (the definition can be pretty broad here). They then choose a category that person belongs to and say "no more [category]". For example: "Amelia Earhart, no more people who have flown a plane". But you could also say "no more people with well-known deaths" or "no more people whose name contains a body part".
Turn moves to the next player, who must satisfy all of the previous conditions. If other players think they have broken one of the rules, they can challenge. If it is determined (usually by consensus) that their person belonged to a previous category, they are eliminated.
Popular house rules include being eliminated after two incorrect challenges, and a 2-minute internet search rule for challenges.
Materials: Deck of cards (or the pieces from another game, if you're brave)
Players: 4-8
In my opinion, the platonic ideal of a party game. There are many sets of house rules available, the ones I use a fairly simple.
One player is designated Mao. Usually some initial rules are decided: play passes clockwise, and a turn consists of playing a single card. The first player to empty their hand of seven cards wins the round. If any player breaks a rule Mao says "you broke a rule" and gives them a card.
The winner of the round then decides a new rule to introduce and informs Mao privately. A new round starts, and rules accumulate as play goes on.
Examples of rules include "aces are skips", "you must play your card with your left hand", "cards must alternate colours" or "you may not talk on your turn". Mao may like to distinguish card rules from behavioural rules when punishing players.
The game continues until everyone is clearly not having fun anymore. This will take different amounts of time depending on the group. At some point I might make a large list of possible rules.