Games that survive somebody leaving halfway through

The party is not a fixed set of people

At any real gathering, the group playing at 9pm is not the group that was playing at 8. Somebody went to help in the kitchen. Two people arrived. Somebody's child needs putting to bed and they will be back in twenty minutes, probably.

Most party games treat this as a fault condition. The turn order breaks, a team is short, the scores stop meaning anything, and there is a small negotiation about whether to restart that usually ends with the game quietly not restarting.

A handful of games do not care at all, and knowing which is which is worth more at a party than knowing which games are best.

The test: does the game hold anything per player?

That is the whole distinction. A game where each player accumulates something — a hand of cards, a position on a board, a role, a score that the mechanics depend on — cannot lose a player cleanly, because their accumulated thing is still sitting there affecting everyone else.

A game where the state lives in the middle of the table, and players are just the people currently looking at it, loses a player for free. Nobody has to decide what happens to their stuff, because they did not have any.

This is also why "can somebody join late" and "can somebody leave" are the same question with the same answer, and why a game that handles one usually handles both.

What passes

Tambola is the extreme case and the reason every Indian family gathering has ended up playing it. Numbers get called into the room; you either have a ticket or you do not. Somebody joining at call forty is behind, but they are playing, immediately, with no explanation and no adjustment by anyone else. It seats a genuinely large room, and it is the one game here designed so people can join in the middle.

Word Chain and Atlas both survive anything. The state is one word. If four people leave, the chain continues; if three arrive, they are in from the next word, and nobody has to explain a scoring system because there is barely one.

Reaction Grid works for the same reason in the opposite register. Every round is independent and lasts seconds, so the roster at the start of a round is simply the roster, and the previous round has no opinion about it.

What to do with the games that do not

Do not try to make them cope. A social deduction game with a missing player is a broken game, and patching it mid-round — assigning their role to someone, playing on with a dead seat — is worse than stopping, because the room now suspects the patch.

The move is to schedule them. Run the games that need a stable roster in the middle of the evening, when everybody who is coming has come and nobody has started leaving, and bookend them with games that do not care. The first half hour and the last are for the interruptible games, and that is not a compromise — those are the periods when a game that can absorb chaos is more fun than one that cannot.