A Membership Game
Granny Doesn't Like Tea is an example of a secret rule game.
A secret rule game is a playful, often puzzling group activity where one or a few players know a secret rule that determines what fits or happens in the game, while the rest of the players must figure it out through observation and deduction. The fun lies in the mix of confusion, clever hints, and the "aha!" moment when players crack the code, making these games perfect for sparking laughter and creative thinking in social settings.
Like all secret rule games, Granny Doesn't Like Tea is played in a group where some, but not all, players know the secret rule.
Granny Doesn't Like Tea is also an example of a Membership game.
In a Membership game, gameplay revolves around organizing things into groups based on a specific quality. Anything that can be discussed — a person, place, thing, or otherwise — may or may not have that quality. Players who know the secret rule understand the criteria that determine whether something is what Granny likes.
Gameplay in Granny Doesn't Like Tea revolves around players gathering examples of something that either is what Granny likes, or not.
There are two ways examples can be provided. First, a player who knows the secret rule can volunteer an example, identifying whether it is what Granny likes. When providing examples, it is often helpful to offer two things that are similar in some respects, but only one of which is what Granny likes — the contrast gives the other players something to reason about.
Second, players who don't yet know the rule can suggest something new and ask the knowers whether it is what Granny likes. Knowers respond at the same time, building up a body of examples for the unknowers to deduce from. While questions will almost always be answered with "yes" or "no", there are some cases where the answer may be less concrete, which can give players further clues about the secret rule.
The game ends when all players have figured out the rule and can agree on whether something is what Granny likes reliably. Those players will no longer be able to play that particular game, but there are plenty of other secret rule games to try next.
Reveal the secret to Granny Doesn't Like Tea
Granny likes a thing if and only if its name doesn't contain the letter "T".
This game has one of the more straightforward secret rules, so there are fewer things to consider when playing it. One thing worth mentioning is that the clever title of the game, which can be heard as Granny Doesn't Like T, can sometimes give away the rule too quickly, especially when playing with people who already know the secret rules to other secret rule games.
My recommendation is that the title should be slightly modified when playing with experienced players, to something slightly more misleading.
Examples:
The addition of even one extra red herring detail into the title of the game can make it a little harder to figure out the secret rule, making the game last longer.