No board, no app, mostly no equipment at all.
The two things that actually decide whether a party game works are how many people are in the room and whether they know each other. Everything else is taste.
One practical note: games where a single person has to run it and not play (Werewolf) need a volunteer who is genuinely happy to sit out. Games where everyone plays every round tend to survive a long night better.
Everyone shares a secret word except the spies. Ask each other questions until you can name who does not know it — without saying the word out loud.
Everyone writes a few names or phrases. Three rounds with the same slips: describe freely, then one word only, then mime. The repetition is what makes it funny.
Secret werewolves eliminate a villager each night; the village votes someone out each day. Needs one person to run it and not play.
Each person states three things about themselves. The group votes on which is invented. Best early in a night with people who half-know each other.
Say something you have never done. Anyone who has done it puts a finger down. Sets the tone fast — choose your group accordingly.
Pick a category and go round naming things in it, keeping a rhythm. Repeat, hesitate or break the beat and you are out.
Act out a film, book or phrase with no words while your team guesses against a timer. Works at any age and never needs explaining twice.
One secret murderer eliminates people by winking at them. Everyone else tries to spot the wink before they are out. Best standing up and mingling.
Everyone writes a famous name and sticks it on the person to their left. Ask yes/no questions until you work out who you are.
Build a single story around the circle, one word each. Falls apart quickly and that is the point.
Offer two bad options and make everyone choose, then defend it. Better with a rule that you must justify your answer.
One person thinks of a word and gives its first letter. Others try to make contact by clueing words starting with that letter to each other.
It is the only one here that needs no explanation longer than a sentence, works from three people to twelve, and produces an actual argument at the end. Everyone shares a secret word except one or two spies. You ask each other questions. Then you vote.
It runs on one phone that gets passed around, so nobody needs to download anything, and it works offline once the page has loaded. There is a full rules page, a list of questions if the table goes quiet, and a strategy guide for when your group gets good at it.
Six is close to ideal for social deduction — the spy game, Werewolf and Fishbowl all work well at that size. Anything requiring teams splits cleanly into two threes.
Two truths and a lie, charades, categories, wink murder, contact and would-you-rather need nothing at all. The spy game needs one phone between everyone.
Fishbowl and Werewolf scale past twelve better than most. Wink murder works well if people can move around rather than sit in a circle.
The spy game runs from three. Two truths and a lie, categories and contact also work at that size, where anything team-based does not.
Two truths and a lie, because the content is the introductions. Follow it with something with a clear goal, like the spy game, once people have relaxed.