Indirect mode

In indirect mode, the guessers take turns (either in sequence or informally) to think of someone with the designated initial letter. Each guesser asks the chooser a yes/no question using some fact about the guesser's choice. For example, if the letter is B then the guesser might choose Yul Brynner and ask, "Are you bald?" At this point, the chooser has three possible responses:

1. "No, I am not Frank Black." — The chooser has thought of a person who matches the criterion of the guesser's question and is not the chooser's identity. Typically this will be the person the guesser is thinking of, but any other person who matches the question is acceptable. The game remains in indirect mode, and moves to the next guesser.
2. "Yes, I am Yul Brynner." — The chooser's identity meets the criterion of the guesser's question, and the chooser cannot think of anyone else who satisfies it. The guesser wins.
3. "No, and I don't know who you're thinking of." — The chooser can't think of someone meeting the criteria. The guesser reveals their answer, and the game changes to direct mode.

Guessers can use indirect mode to guess the chooser's identity directly (e.g. "Are you Yul Brynner?").

Although the guesser's questions is in the form "Are you...?", it is not necessary for the guesser to choose a person who matches what they have already learned about the chooser's identity. The bar of acceptability for guesser choices is lower than that for the chooser's identity; it is not essential for the chooser to have heard of the person, or to know the relevant biographical detail, but guessers should not deliberately exploit this provision.

Direct mode

In direct mode, the guesser whose choice enabled the mode switch gets to ask one or more yes/no questions about the chooser's identity, as in Twenty Questions. In some variants, direct mode continues until the chooser answers "no" to a question; some variants allow only a single direct-mode question before returning to indirect mode, regardless of the answer.

If the chooser does not know the answer to a direct mode question, or the question does not permit a clear-cut yes/no answer, then the chooser answers as accurately as possible. There are some conventions for answering contextually inappropriate direct mode questions; for example, fictional characters are usually deemed to be dead if their death has been recorded.

Winning

The game ends when a guesser successfully determines the chooser's identity. That guesser then becomes the chooser, a new identity and letter are chosen and the game starts again in indirect mode. If the successful guess was suggested by a non-designated guesser in direct mode, then it is normal courtesy for the designated guesser to defer to the other player.

If all guessers give up before winning, then the chooser reveals the identity. The guessers then determine (by majority) whether the choice was a good one (that is, they should all have known of the character and the chooser's answers in direct mode were reasonably accurate). The role of chooser then remains with the same player, or passes to another player (e.g. clockwise) as appropriate. It is considered bad form for one guesser to hold out after everyone else has given up.

Stumping

This variant is particularly useful as a pastime for long trips, since a single round can sometimes last over an hour. As in the standard version, the chooser picks a famous person or character and provides an initial (for example, if the chooser picked Sandro Botticelli, he or she would provide the letter "B"). The guesser must then think of a trivia question which can be answered by a word beginning with that letter, so in our example the guesser might ask, "What is the most populous country in South America?", the answer being "Brazil." The answer to the question must be something the chooser could reasonably know, not something personal to the guesser (e.g. "What was the name of my invisible friend when I was five?") or anything otherwise impossible to guess. If the chooser answers correctly, the guesser must think of another question. If the chooser is stumped and cannot answer, the guesser may ask a single yes-or-no question (as in direct mode of the standard version) about the person or character. Once the chooser answers the question, the guesser must stump the chooser again before asking another direct question. Generally, guessing the identity of the person or character counts as a direct question and can only be done after the chooser is stumped; however, in the interest of shortening the game, players sometimes will guess the person without having first stumped the chooser.

Confirmation requirement

In one variation, the game only moves to direct mode if, after the chooser fails or gives up, another guesser can successfully identify the subject of the question. This provides a built-in standard for whether the question posed by the guesser was fair.

Additional letters

One variation rewards stumping the chooser (but not fellow guessers) with an additional letter in the chosen person's name. This can make for quicker gameplay.

Narrowing down choices

This variation requires that indirect questions include all the criteria thus far established. So if it has been determined that the mystery person is a living male movie star, the next question must be about a living male movie star, and so on. This adds a new degree of difficulty, while more directly channeling the game closer to the correct answer.

Another variation on this variation is to start not with a letter, but from scratch.