How to Play 21 Questions Over Text

One player thinks of a person, place, or thing. They text the other player the category (for example, "I'm thinking of a person") to get things started.
The guesser sends yes-or-no questions one at a time. Start broad ("Is this person alive?") and narrow down from there.
The answerer replies honestly with "yes" or "no" to each question. No misleading answers or trick responses.
The guesser has exactly 21 questions to figure out the answer. If they get it right, they win. If not, the answerer reveals the answer and they swap roles.

Rules

Questions must be answerable with "yes" or "no." No open-ended questions like "What color is it?"
The answerer must respond honestly every time. No trick answers or deliberate misdirection.
The guesser gets exactly 21 questions. Keep count so nobody loses track.
The guesser can make a final guess at any point, but it counts as one of their 21 questions.
Pick something the other person could reasonably know or figure out. Obscure inside jokes are no fun.

You

ok I'm thinking of a thing. go!

Them

is it something you can hold in your hand?

You

yes

Them

is it electronic?

You

nope

Them

is it something you'd find in a kitchen?

You

yes! getting warmer

Them

is it a spatula 😂 idk why that was my first thought

Start with broad category questions (alive? man-made? bigger than a car?) to eliminate large groups quickly before getting specific.
Try a "personal" version where you can only pick things related to your own life, like a favorite movie or a place you have visited.
Play a speed round where each player has only 60 seconds to send their next question. Keeps the energy up.
Number your questions as you go (Q1, Q2, Q3...) so both players can easily track how many are left.